Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Jacopo,
On Saturday, 10 March 2018 20:00:31 EET jacopo mondi wrote:
> On Sat, Mar 10, 2018 at 11:23:19AM +0530, Archit Taneja wrote:
> > On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
> > > Hello,
> > >
> > > after some discussion on the proposed bindings for generic lvds
> > > decoder and Thine THC63LVD1024, I decided to drop the THC63 specific
> > > part and just live with a transparent decoder that does not support any
> > > configuration from DT.
> > >
> > > Dropping THC63 support to avoid discussion on how to better implement
> > > support for a DRM bridge with 2 input ports and focus on LVDS mode
> > > propagation through bridges as explained in v1 cover letter (for DRM
> > > people: please see [1] as why I find difficult to implement support for
> > > bridges with multiple input endpoints)
> > >
> > > Same base branch as v1, with same patches for V3M Eagle applied on top.
> > > git://jmondi.org/linux v3m/v4.16-rc3/base
> > >
> > > Thanks
> > >
> > >j
> > >
> > > v1 -> v2:
> > > - Drop support for THC63LVD1024
> > >
> > > [1] I had a quick at how to model a DRM bridge with multiple input
> > > ports, and I see a blocker in how DRM identifies and matches bridges
> > > using the devices node in place of the endpoint nodes.
> > >
> > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see
> > > only a few ways to support that:
> > >
> > > 1) register 2 drm bridges from the same driver (one for each
> > > input/output pair) but they would both be matches on the same device
> > > node when the preceding bridge calls "of_drm_find_bridge()".
> >
> > I think this is the way to go. DRM doesn't say anywhere that we can't have
> > 2 drm_bridge-s contained in a single device.
I agree, but it only works as long as the two bridges are independent. The
THC63LVD1024 can also work in single-in, dual-out and dual-in, single-out
modes, in which case we will need a more generic solution. I'm fine ignoring
the problem on the driver side for now until someone needs to support such a
setup, but the DT bindings need to be right.
> > About the issue with
> > of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
> > the bridge1 and bridge2 nodes as shown below, wouldn't that suffice. From
> > what I know, we don't necessarily need to set the bridge's of_node
> > to the device (i.e, thschip) itself.
>
> That's fine, but this implies that the preceding bridge (or encoder) in the
> DRM pipeline has then to collect the "port" node and match on it
> specifically when it attaches this driver. This introduces an ad-hoc
> policy that prevents this driver from being easily integrated in
> existing pipelines (where bridges are matched on the device node).
>
> Also, I don't know much about the DRM framework, but it seems to me
> that the helper function designed to find the next component to attach
> to in the DRM pipeline is:
>
> drm_of_find_panel_or_bridge():
> remote = of_graph_get_remote_node();
> ep = of_graph_get_endpoint_by_regs();
> return of_graph_get_remote_port_parent(); <-- This returns
> the device node of_drm_find_panel(remote);
> of_drm_find_bridge(remote);
>
> I so dare to say matching on device node is kind of the intended way
> to do things in DRM, and this driver with two endpoints that wants to
> be matched on port nodes would be kind of special one that does not
> work as other driver expects to.
>
> Is my understanding correct, or have I misinterpreted something?
I agree with you, so I hope your understanding is correct :-) We have the
exact same issue in V4L2 where we used to always match on the device node, but
recently the ADV7482 required matching on port nodes. The solution that was
proposed was to support matching on both the device node and the port nodes,
with automatic lookup of the device node from the port node if no direct match
is found. I think this would work well in DRM too. Regardless of what we
decide to do, we need to ensure that we don't create two separate categories
of bridges with different matching rules that won't be compatible.
> > thschip {
> > ...
> > ports {
> > bridge1: port@0 {
> > ...
> > };
> > bridge2: port@1 {
> > ...
> > };
> > };
> > };
> >
> > > 2) register a single bridge with multiple "next bridges", but when the
> > > bridge gets attached I don't see a way on how to identify on which
> > > next bridge "drm_bridge_attach()" on, as it depends on the endpoint
> > > the current bridge has been attached on first, and we don't have
> > > that information.
For the general case I think we'll need to start adding port index arguments
to the bridge API, but as stated above I'm fine ignoring this for now and
creating two bridges.
> > > 3) Register more instances of the same chip in DTS, one for each
> > > input/output pair. They gonna
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Jacopo,
On Saturday, 10 March 2018 20:00:31 EET jacopo mondi wrote:
> On Sat, Mar 10, 2018 at 11:23:19AM +0530, Archit Taneja wrote:
> > On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
> > > Hello,
> > >
> > > after some discussion on the proposed bindings for generic lvds
> > > decoder and Thine THC63LVD1024, I decided to drop the THC63 specific
> > > part and just live with a transparent decoder that does not support any
> > > configuration from DT.
> > >
> > > Dropping THC63 support to avoid discussion on how to better implement
> > > support for a DRM bridge with 2 input ports and focus on LVDS mode
> > > propagation through bridges as explained in v1 cover letter (for DRM
> > > people: please see [1] as why I find difficult to implement support for
> > > bridges with multiple input endpoints)
> > >
> > > Same base branch as v1, with same patches for V3M Eagle applied on top.
> > > git://jmondi.org/linux v3m/v4.16-rc3/base
> > >
> > > Thanks
> > >
> > >j
> > >
> > > v1 -> v2:
> > > - Drop support for THC63LVD1024
> > >
> > > [1] I had a quick at how to model a DRM bridge with multiple input
> > > ports, and I see a blocker in how DRM identifies and matches bridges
> > > using the devices node in place of the endpoint nodes.
> > >
> > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see
> > > only a few ways to support that:
> > >
> > > 1) register 2 drm bridges from the same driver (one for each
> > > input/output pair) but they would both be matches on the same device
> > > node when the preceding bridge calls "of_drm_find_bridge()".
> >
> > I think this is the way to go. DRM doesn't say anywhere that we can't have
> > 2 drm_bridge-s contained in a single device.
I agree, but it only works as long as the two bridges are independent. The
THC63LVD1024 can also work in single-in, dual-out and dual-in, single-out
modes, in which case we will need a more generic solution. I'm fine ignoring
the problem on the driver side for now until someone needs to support such a
setup, but the DT bindings need to be right.
> > About the issue with
> > of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
> > the bridge1 and bridge2 nodes as shown below, wouldn't that suffice. From
> > what I know, we don't necessarily need to set the bridge's of_node
> > to the device (i.e, thschip) itself.
>
> That's fine, but this implies that the preceding bridge (or encoder) in the
> DRM pipeline has then to collect the "port" node and match on it
> specifically when it attaches this driver. This introduces an ad-hoc
> policy that prevents this driver from being easily integrated in
> existing pipelines (where bridges are matched on the device node).
>
> Also, I don't know much about the DRM framework, but it seems to me
> that the helper function designed to find the next component to attach
> to in the DRM pipeline is:
>
> drm_of_find_panel_or_bridge():
> remote = of_graph_get_remote_node();
> ep = of_graph_get_endpoint_by_regs();
> return of_graph_get_remote_port_parent(); <-- This returns
> the device node of_drm_find_panel(remote);
> of_drm_find_bridge(remote);
>
> I so dare to say matching on device node is kind of the intended way
> to do things in DRM, and this driver with two endpoints that wants to
> be matched on port nodes would be kind of special one that does not
> work as other driver expects to.
>
> Is my understanding correct, or have I misinterpreted something?
I agree with you, so I hope your understanding is correct :-) We have the
exact same issue in V4L2 where we used to always match on the device node, but
recently the ADV7482 required matching on port nodes. The solution that was
proposed was to support matching on both the device node and the port nodes,
with automatic lookup of the device node from the port node if no direct match
is found. I think this would work well in DRM too. Regardless of what we
decide to do, we need to ensure that we don't create two separate categories
of bridges with different matching rules that won't be compatible.
> > thschip {
> > ...
> > ports {
> > bridge1: port@0 {
> > ...
> > };
> > bridge2: port@1 {
> > ...
> > };
> > };
> > };
> >
> > > 2) register a single bridge with multiple "next bridges", but when the
> > > bridge gets attached I don't see a way on how to identify on which
> > > next bridge "drm_bridge_attach()" on, as it depends on the endpoint
> > > the current bridge has been attached on first, and we don't have
> > > that information.
For the general case I think we'll need to start adding port index arguments
to the bridge API, but as stated above I'm fine ignoring this for now and
creating two bridges.
> > > 3) Register more instances of the same chip in DTS, one for each
> > > input/output pair. They gonna
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Andrzej, thanks for the detailed reply, much appreciated :) On Mon, Mar 12, 2018 at 02:47:20PM +0100, Andrzej Hajda wrote: > On 12.03.2018 13:30, jacopo mondi wrote: > > Hi Andrzej, > > > > On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: > >> [snip] > > I understand. The "transparent bridge" is of no actual use, but I don't see > > how the "double bridge" thing is not an issue if I were to develop > > support for the actual Thine chip. > > What is exactly your configuration: single/dual input, single/dual output? > Current bindings suggests single/single, am I right? In such case you do > not need to implement dual link functionality in the driver - since you > even do not have possibility to test it. Correct, I'm running in single/single mode. > But the bindings should support all modes of operation, or at least > should be easy to extend them in the future with backward compatibility. > And here is where I always get lost. For sake of being compatible with future extensions, bindings shall describe hardware, not what is currently supported in driver. One day I'll get this right! > > > > Please see my reply from yesterday to Archit. I still think having two > > bridges is somehow an issue... > > Yes, I agree. But do we have such case? If no - no problem ATM :), if > yes - lets try to implement it and see where is the problem, as Archit > already suggested it would be just a matter of assigning bridge to port > node, instead of device node. > Again, I've been fooled by the idea that if bindings describe something, the driver should implement it (but I'm still not sure that "just assign the port node to the bridge" is the right thing to do here, but let's leave this out for now :) > > > > While we clarify that, would it be fine an initial driver version for > > the actualt Thine chip with a single input support[1]? I would ditch this > > transparent bridge and resume working on a THC63LVD1024 driver from > > comments received on v1. > > I think, yes: driver with only single input, and full or extend-able > bindings. > > > > > Thanks > > j > > > > [1] Single input support implies a single input port in DT bindings > > even if the chip supports two, and my understanding was that you > > didn't like this. > > I am sorry if I was not clear enough, only thing I wanted was complete > or at least consistent/extend-able binding. > So when I saw word "multiple LVDS streams" in bindings I was looking > further to see how these multiple LVDS bindings are defined, and found > nothing :) No worries, you're right here, again it's me confused by bindings description vs driver features... > Btw I think it may be better to use "Dual Link" instead of "Multiple > streams", it is more precise and quite well established in docs. Ack, I will follow up with a v3 where I'll get rid of generic LVDS decoder and target the actual chip. Thanks j > > Regards > Andrzej > > > > > > >> Regards > >> Andrzej > >> > >>> Jacopo Mondi (3): > >>> dt-bindings: display: bridge: Document LVDS to parallel decoder > >>> drm: bridge: Add LVDS decoder driver > >>> arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > >>> > >>> .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > >>> arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > >>> drivers/gpu/drm/bridge/Kconfig | 8 ++ > >>> drivers/gpu/drm/bridge/Makefile| 1 + > >>> drivers/gpu/drm/bridge/lvds-decoder.c | 157 > >>> + > >>> 5 files changed, 237 insertions(+), 2 deletions(-) > >>> create mode 100644 > >>> Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > >>> create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > >>> > >>> -- > >>> 2.7.4 > >>> > >>> > >>> > >>> > signature.asc Description: PGP signature
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Andrzej, thanks for the detailed reply, much appreciated :) On Mon, Mar 12, 2018 at 02:47:20PM +0100, Andrzej Hajda wrote: > On 12.03.2018 13:30, jacopo mondi wrote: > > Hi Andrzej, > > > > On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: > >> [snip] > > I understand. The "transparent bridge" is of no actual use, but I don't see > > how the "double bridge" thing is not an issue if I were to develop > > support for the actual Thine chip. > > What is exactly your configuration: single/dual input, single/dual output? > Current bindings suggests single/single, am I right? In such case you do > not need to implement dual link functionality in the driver - since you > even do not have possibility to test it. Correct, I'm running in single/single mode. > But the bindings should support all modes of operation, or at least > should be easy to extend them in the future with backward compatibility. > And here is where I always get lost. For sake of being compatible with future extensions, bindings shall describe hardware, not what is currently supported in driver. One day I'll get this right! > > > > Please see my reply from yesterday to Archit. I still think having two > > bridges is somehow an issue... > > Yes, I agree. But do we have such case? If no - no problem ATM :), if > yes - lets try to implement it and see where is the problem, as Archit > already suggested it would be just a matter of assigning bridge to port > node, instead of device node. > Again, I've been fooled by the idea that if bindings describe something, the driver should implement it (but I'm still not sure that "just assign the port node to the bridge" is the right thing to do here, but let's leave this out for now :) > > > > While we clarify that, would it be fine an initial driver version for > > the actualt Thine chip with a single input support[1]? I would ditch this > > transparent bridge and resume working on a THC63LVD1024 driver from > > comments received on v1. > > I think, yes: driver with only single input, and full or extend-able > bindings. > > > > > Thanks > > j > > > > [1] Single input support implies a single input port in DT bindings > > even if the chip supports two, and my understanding was that you > > didn't like this. > > I am sorry if I was not clear enough, only thing I wanted was complete > or at least consistent/extend-able binding. > So when I saw word "multiple LVDS streams" in bindings I was looking > further to see how these multiple LVDS bindings are defined, and found > nothing :) No worries, you're right here, again it's me confused by bindings description vs driver features... > Btw I think it may be better to use "Dual Link" instead of "Multiple > streams", it is more precise and quite well established in docs. Ack, I will follow up with a v3 where I'll get rid of generic LVDS decoder and target the actual chip. Thanks j > > Regards > Andrzej > > > > > > >> Regards > >> Andrzej > >> > >>> Jacopo Mondi (3): > >>> dt-bindings: display: bridge: Document LVDS to parallel decoder > >>> drm: bridge: Add LVDS decoder driver > >>> arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > >>> > >>> .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > >>> arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > >>> drivers/gpu/drm/bridge/Kconfig | 8 ++ > >>> drivers/gpu/drm/bridge/Makefile| 1 + > >>> drivers/gpu/drm/bridge/lvds-decoder.c | 157 > >>> + > >>> 5 files changed, 237 insertions(+), 2 deletions(-) > >>> create mode 100644 > >>> Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > >>> create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > >>> > >>> -- > >>> 2.7.4 > >>> > >>> > >>> > >>> > signature.asc Description: PGP signature
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
On 12.03.2018 13:30, jacopo mondi wrote: > Hi Andrzej, > > On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: >> On 09.03.2018 14:51, Jacopo Mondi wrote: >>> Hello, >>>after some discussion on the proposed bindings for generic lvds decoder >>> and >>> Thine THC63LVD1024, I decided to drop the THC63 specific part and just live >>> with >>> a transparent decoder that does not support any configuration from DT. >>> >>> Dropping THC63 support to avoid discussion on how to better implement >>> support >>> for a DRM bridge with 2 input ports and focus on LVDS mode propagation >>> through >>> bridges as explained in v1 cover letter (for DRM people: please see [1] as >>> why >>> I find difficult to implement support for bridges with multiple input >>> endpoints) >>> >>> Same base branch as v1, with same patches for V3M Eagle applied on top. >>> git://jmondi.org/linux v3m/v4.16-rc3/base >>> >>> Thanks >>>j >>> >>> v1 -> v2: >>> - Drop support for THC63LVD1024 >>> >>> [1] I had a quick at how to model a DRM bridge with multiple input >>> ports, and I see a blocker in how DRM identifies and matches bridges using >>> the devices node in place of the endpoint nodes. >>> >>> As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only >>> a few ways to support that: >>> 1) register 2 drm bridges from the same driver (one for each input/output >>> pair) >>> but they would both be matches on the same device node when the >>> preceding >>> bridge calls "of_drm_find_bridge()". >>> 2) register a single bridge with multiple "next bridges", but when the >>> bridge >>> gets attached I don't see a way on how to identify on which next bridge >>> "drm_bridge_attach()" on, as it depends on the endpoint the current >>> bridge >>> has been attached on first, and we don't have that information. >>> 3) Register more instances of the same chip in DTS, one for each >>> input/output >>> pair. They gonna share supplies and gpios, and I don't like that. >>> >>> I had a quick look at the currently in mainline bridges and none of them has >>> multiple input endpoints, except for HDMI audio endpoint, which I haven't >>> found >>> in use in any DTS. I guess the problem has been already debated and maybe >>> solved >>> in the past, so feel free to point me to other sources. >> I think this is is a step in wrong direction, IMHO. Your previous >> patchset was quite OK, at least bindings, IMHO. Few things needed only >> polishing. >> Here we have unmanaged/transparent bridge, which is totally different, >> what happened to regulators and gpios from previous iteration. >> I do not have schematics of the board, but I guess respective pins of >> the bridge must be connected somehow. >> I think the problem you want to avoid (double bridge) should not be a >> problem at all. >> I suppose the most important is to have correct bindings - as they need >> to be stable. >> If you really must to do hacks better is to put them into driver. >> > I understand. The "transparent bridge" is of no actual use, but I don't see > how the "double bridge" thing is not an issue if I were to develop > support for the actual Thine chip. What is exactly your configuration: single/dual input, single/dual output? Current bindings suggests single/single, am I right? In such case you do not need to implement dual link functionality in the driver - since you even do not have possibility to test it. But the bindings should support all modes of operation, or at least should be easy to extend them in the future with backward compatibility. > > Please see my reply from yesterday to Archit. I still think having two > bridges is somehow an issue... Yes, I agree. But do we have such case? If no - no problem ATM :), if yes - lets try to implement it and see where is the problem, as Archit already suggested it would be just a matter of assigning bridge to port node, instead of device node. > > While we clarify that, would it be fine an initial driver version for > the actualt Thine chip with a single input support[1]? I would ditch this > transparent bridge and resume working on a THC63LVD1024 driver from > comments received on v1. I think, yes: driver with only single input, and full or extend-able bindings. > > Thanks > j > > [1] Single input support implies a single input port in DT bindings > even if the chip supports two, and my understanding was that you > didn't like this. I am sorry if I was not clear enough, only thing I wanted was complete or at least consistent/extend-able binding. So when I saw word "multiple LVDS streams" in bindings I was looking further to see how these multiple LVDS bindings are defined, and found nothing :) Btw I think it may be better to use "Dual Link" instead of "Multiple streams", it is more precise and quite well established in docs. Regards Andrzej > > >> Regards >> Andrzej >> >>> Jacopo Mondi (3): >>> dt-bindings: display: bridge: Document LVDS to parallel
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
On 12.03.2018 13:30, jacopo mondi wrote: > Hi Andrzej, > > On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: >> On 09.03.2018 14:51, Jacopo Mondi wrote: >>> Hello, >>>after some discussion on the proposed bindings for generic lvds decoder >>> and >>> Thine THC63LVD1024, I decided to drop the THC63 specific part and just live >>> with >>> a transparent decoder that does not support any configuration from DT. >>> >>> Dropping THC63 support to avoid discussion on how to better implement >>> support >>> for a DRM bridge with 2 input ports and focus on LVDS mode propagation >>> through >>> bridges as explained in v1 cover letter (for DRM people: please see [1] as >>> why >>> I find difficult to implement support for bridges with multiple input >>> endpoints) >>> >>> Same base branch as v1, with same patches for V3M Eagle applied on top. >>> git://jmondi.org/linux v3m/v4.16-rc3/base >>> >>> Thanks >>>j >>> >>> v1 -> v2: >>> - Drop support for THC63LVD1024 >>> >>> [1] I had a quick at how to model a DRM bridge with multiple input >>> ports, and I see a blocker in how DRM identifies and matches bridges using >>> the devices node in place of the endpoint nodes. >>> >>> As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only >>> a few ways to support that: >>> 1) register 2 drm bridges from the same driver (one for each input/output >>> pair) >>> but they would both be matches on the same device node when the >>> preceding >>> bridge calls "of_drm_find_bridge()". >>> 2) register a single bridge with multiple "next bridges", but when the >>> bridge >>> gets attached I don't see a way on how to identify on which next bridge >>> "drm_bridge_attach()" on, as it depends on the endpoint the current >>> bridge >>> has been attached on first, and we don't have that information. >>> 3) Register more instances of the same chip in DTS, one for each >>> input/output >>> pair. They gonna share supplies and gpios, and I don't like that. >>> >>> I had a quick look at the currently in mainline bridges and none of them has >>> multiple input endpoints, except for HDMI audio endpoint, which I haven't >>> found >>> in use in any DTS. I guess the problem has been already debated and maybe >>> solved >>> in the past, so feel free to point me to other sources. >> I think this is is a step in wrong direction, IMHO. Your previous >> patchset was quite OK, at least bindings, IMHO. Few things needed only >> polishing. >> Here we have unmanaged/transparent bridge, which is totally different, >> what happened to regulators and gpios from previous iteration. >> I do not have schematics of the board, but I guess respective pins of >> the bridge must be connected somehow. >> I think the problem you want to avoid (double bridge) should not be a >> problem at all. >> I suppose the most important is to have correct bindings - as they need >> to be stable. >> If you really must to do hacks better is to put them into driver. >> > I understand. The "transparent bridge" is of no actual use, but I don't see > how the "double bridge" thing is not an issue if I were to develop > support for the actual Thine chip. What is exactly your configuration: single/dual input, single/dual output? Current bindings suggests single/single, am I right? In such case you do not need to implement dual link functionality in the driver - since you even do not have possibility to test it. But the bindings should support all modes of operation, or at least should be easy to extend them in the future with backward compatibility. > > Please see my reply from yesterday to Archit. I still think having two > bridges is somehow an issue... Yes, I agree. But do we have such case? If no - no problem ATM :), if yes - lets try to implement it and see where is the problem, as Archit already suggested it would be just a matter of assigning bridge to port node, instead of device node. > > While we clarify that, would it be fine an initial driver version for > the actualt Thine chip with a single input support[1]? I would ditch this > transparent bridge and resume working on a THC63LVD1024 driver from > comments received on v1. I think, yes: driver with only single input, and full or extend-able bindings. > > Thanks > j > > [1] Single input support implies a single input port in DT bindings > even if the chip supports two, and my understanding was that you > didn't like this. I am sorry if I was not clear enough, only thing I wanted was complete or at least consistent/extend-able binding. So when I saw word "multiple LVDS streams" in bindings I was looking further to see how these multiple LVDS bindings are defined, and found nothing :) Btw I think it may be better to use "Dual Link" instead of "Multiple streams", it is more precise and quite well established in docs. Regards Andrzej > > >> Regards >> Andrzej >> >>> Jacopo Mondi (3): >>> dt-bindings: display: bridge: Document LVDS to parallel
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Andrzej, On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: > On 09.03.2018 14:51, Jacopo Mondi wrote: > > Hello, > >after some discussion on the proposed bindings for generic lvds decoder > > and > > Thine THC63LVD1024, I decided to drop the THC63 specific part and just live > > with > > a transparent decoder that does not support any configuration from DT. > > > > Dropping THC63 support to avoid discussion on how to better implement > > support > > for a DRM bridge with 2 input ports and focus on LVDS mode propagation > > through > > bridges as explained in v1 cover letter (for DRM people: please see [1] as > > why > > I find difficult to implement support for bridges with multiple input > > endpoints) > > > > Same base branch as v1, with same patches for V3M Eagle applied on top. > > git://jmondi.org/linux v3m/v4.16-rc3/base > > > > Thanks > >j > > > > v1 -> v2: > > - Drop support for THC63LVD1024 > > > > [1] I had a quick at how to model a DRM bridge with multiple input > > ports, and I see a blocker in how DRM identifies and matches bridges using > > the devices node in place of the endpoint nodes. > > > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only > > a few ways to support that: > > 1) register 2 drm bridges from the same driver (one for each input/output > > pair) > > but they would both be matches on the same device node when the > > preceding > > bridge calls "of_drm_find_bridge()". > > 2) register a single bridge with multiple "next bridges", but when the > > bridge > > gets attached I don't see a way on how to identify on which next bridge > > "drm_bridge_attach()" on, as it depends on the endpoint the current > > bridge > > has been attached on first, and we don't have that information. > > 3) Register more instances of the same chip in DTS, one for each > > input/output > > pair. They gonna share supplies and gpios, and I don't like that. > > > > I had a quick look at the currently in mainline bridges and none of them has > > multiple input endpoints, except for HDMI audio endpoint, which I haven't > > found > > in use in any DTS. I guess the problem has been already debated and maybe > > solved > > in the past, so feel free to point me to other sources. > > I think this is is a step in wrong direction, IMHO. Your previous > patchset was quite OK, at least bindings, IMHO. Few things needed only > polishing. > Here we have unmanaged/transparent bridge, which is totally different, > what happened to regulators and gpios from previous iteration. > I do not have schematics of the board, but I guess respective pins of > the bridge must be connected somehow. > I think the problem you want to avoid (double bridge) should not be a > problem at all. > I suppose the most important is to have correct bindings - as they need > to be stable. > If you really must to do hacks better is to put them into driver. > I understand. The "transparent bridge" is of no actual use, but I don't see how the "double bridge" thing is not an issue if I were to develop support for the actual Thine chip. Please see my reply from yesterday to Archit. I still think having two bridges is somehow an issue... While we clarify that, would it be fine an initial driver version for the actualt Thine chip with a single input support[1]? I would ditch this transparent bridge and resume working on a THC63LVD1024 driver from comments received on v1. Thanks j [1] Single input support implies a single input port in DT bindings even if the chip supports two, and my understanding was that you didn't like this. > Regards > Andrzej > > > > > Jacopo Mondi (3): > > dt-bindings: display: bridge: Document LVDS to parallel decoder > > drm: bridge: Add LVDS decoder driver > > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > > > > .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > > drivers/gpu/drm/bridge/Kconfig | 8 ++ > > drivers/gpu/drm/bridge/Makefile| 1 + > > drivers/gpu/drm/bridge/lvds-decoder.c | 157 > > + > > 5 files changed, 237 insertions(+), 2 deletions(-) > > create mode 100644 > > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > > > > -- > > 2.7.4 > > > > > > > > > signature.asc Description: PGP signature
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi Andrzej, On Mon, Mar 12, 2018 at 10:07:27AM +0100, Andrzej Hajda wrote: > On 09.03.2018 14:51, Jacopo Mondi wrote: > > Hello, > >after some discussion on the proposed bindings for generic lvds decoder > > and > > Thine THC63LVD1024, I decided to drop the THC63 specific part and just live > > with > > a transparent decoder that does not support any configuration from DT. > > > > Dropping THC63 support to avoid discussion on how to better implement > > support > > for a DRM bridge with 2 input ports and focus on LVDS mode propagation > > through > > bridges as explained in v1 cover letter (for DRM people: please see [1] as > > why > > I find difficult to implement support for bridges with multiple input > > endpoints) > > > > Same base branch as v1, with same patches for V3M Eagle applied on top. > > git://jmondi.org/linux v3m/v4.16-rc3/base > > > > Thanks > >j > > > > v1 -> v2: > > - Drop support for THC63LVD1024 > > > > [1] I had a quick at how to model a DRM bridge with multiple input > > ports, and I see a blocker in how DRM identifies and matches bridges using > > the devices node in place of the endpoint nodes. > > > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only > > a few ways to support that: > > 1) register 2 drm bridges from the same driver (one for each input/output > > pair) > > but they would both be matches on the same device node when the > > preceding > > bridge calls "of_drm_find_bridge()". > > 2) register a single bridge with multiple "next bridges", but when the > > bridge > > gets attached I don't see a way on how to identify on which next bridge > > "drm_bridge_attach()" on, as it depends on the endpoint the current > > bridge > > has been attached on first, and we don't have that information. > > 3) Register more instances of the same chip in DTS, one for each > > input/output > > pair. They gonna share supplies and gpios, and I don't like that. > > > > I had a quick look at the currently in mainline bridges and none of them has > > multiple input endpoints, except for HDMI audio endpoint, which I haven't > > found > > in use in any DTS. I guess the problem has been already debated and maybe > > solved > > in the past, so feel free to point me to other sources. > > I think this is is a step in wrong direction, IMHO. Your previous > patchset was quite OK, at least bindings, IMHO. Few things needed only > polishing. > Here we have unmanaged/transparent bridge, which is totally different, > what happened to regulators and gpios from previous iteration. > I do not have schematics of the board, but I guess respective pins of > the bridge must be connected somehow. > I think the problem you want to avoid (double bridge) should not be a > problem at all. > I suppose the most important is to have correct bindings - as they need > to be stable. > If you really must to do hacks better is to put them into driver. > I understand. The "transparent bridge" is of no actual use, but I don't see how the "double bridge" thing is not an issue if I were to develop support for the actual Thine chip. Please see my reply from yesterday to Archit. I still think having two bridges is somehow an issue... While we clarify that, would it be fine an initial driver version for the actualt Thine chip with a single input support[1]? I would ditch this transparent bridge and resume working on a THC63LVD1024 driver from comments received on v1. Thanks j [1] Single input support implies a single input port in DT bindings even if the chip supports two, and my understanding was that you didn't like this. > Regards > Andrzej > > > > > Jacopo Mondi (3): > > dt-bindings: display: bridge: Document LVDS to parallel decoder > > drm: bridge: Add LVDS decoder driver > > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > > > > .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > > drivers/gpu/drm/bridge/Kconfig | 8 ++ > > drivers/gpu/drm/bridge/Makefile| 1 + > > drivers/gpu/drm/bridge/lvds-decoder.c | 157 > > + > > 5 files changed, 237 insertions(+), 2 deletions(-) > > create mode 100644 > > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > > > > -- > > 2.7.4 > > > > > > > > > signature.asc Description: PGP signature
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
On 09.03.2018 14:51, Jacopo Mondi wrote: > Hello, >after some discussion on the proposed bindings for generic lvds decoder and > Thine THC63LVD1024, I decided to drop the THC63 specific part and just live > with > a transparent decoder that does not support any configuration from DT. > > Dropping THC63 support to avoid discussion on how to better implement support > for a DRM bridge with 2 input ports and focus on LVDS mode propagation through > bridges as explained in v1 cover letter (for DRM people: please see [1] as why > I find difficult to implement support for bridges with multiple input > endpoints) > > Same base branch as v1, with same patches for V3M Eagle applied on top. > git://jmondi.org/linux v3m/v4.16-rc3/base > > Thanks >j > > v1 -> v2: > - Drop support for THC63LVD1024 > > [1] I had a quick at how to model a DRM bridge with multiple input > ports, and I see a blocker in how DRM identifies and matches bridges using > the devices node in place of the endpoint nodes. > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only > a few ways to support that: > 1) register 2 drm bridges from the same driver (one for each input/output > pair) > but they would both be matches on the same device node when the preceding > bridge calls "of_drm_find_bridge()". > 2) register a single bridge with multiple "next bridges", but when the bridge > gets attached I don't see a way on how to identify on which next bridge > "drm_bridge_attach()" on, as it depends on the endpoint the current bridge > has been attached on first, and we don't have that information. > 3) Register more instances of the same chip in DTS, one for each input/output > pair. They gonna share supplies and gpios, and I don't like that. > > I had a quick look at the currently in mainline bridges and none of them has > multiple input endpoints, except for HDMI audio endpoint, which I haven't > found > in use in any DTS. I guess the problem has been already debated and maybe > solved > in the past, so feel free to point me to other sources. I think this is is a step in wrong direction, IMHO. Your previous patchset was quite OK, at least bindings, IMHO. Few things needed only polishing. Here we have unmanaged/transparent bridge, which is totally different, what happened to regulators and gpios from previous iteration. I do not have schematics of the board, but I guess respective pins of the bridge must be connected somehow. I think the problem you want to avoid (double bridge) should not be a problem at all. I suppose the most important is to have correct bindings - as they need to be stable. If you really must to do hacks better is to put them into driver. Regards Andrzej > > Jacopo Mondi (3): > dt-bindings: display: bridge: Document LVDS to parallel decoder > drm: bridge: Add LVDS decoder driver > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > > .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > drivers/gpu/drm/bridge/Kconfig | 8 ++ > drivers/gpu/drm/bridge/Makefile| 1 + > drivers/gpu/drm/bridge/lvds-decoder.c | 157 > + > 5 files changed, 237 insertions(+), 2 deletions(-) > create mode 100644 > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > > -- > 2.7.4 > > > >
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
On 09.03.2018 14:51, Jacopo Mondi wrote: > Hello, >after some discussion on the proposed bindings for generic lvds decoder and > Thine THC63LVD1024, I decided to drop the THC63 specific part and just live > with > a transparent decoder that does not support any configuration from DT. > > Dropping THC63 support to avoid discussion on how to better implement support > for a DRM bridge with 2 input ports and focus on LVDS mode propagation through > bridges as explained in v1 cover letter (for DRM people: please see [1] as why > I find difficult to implement support for bridges with multiple input > endpoints) > > Same base branch as v1, with same patches for V3M Eagle applied on top. > git://jmondi.org/linux v3m/v4.16-rc3/base > > Thanks >j > > v1 -> v2: > - Drop support for THC63LVD1024 > > [1] I had a quick at how to model a DRM bridge with multiple input > ports, and I see a blocker in how DRM identifies and matches bridges using > the devices node in place of the endpoint nodes. > > As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only > a few ways to support that: > 1) register 2 drm bridges from the same driver (one for each input/output > pair) > but they would both be matches on the same device node when the preceding > bridge calls "of_drm_find_bridge()". > 2) register a single bridge with multiple "next bridges", but when the bridge > gets attached I don't see a way on how to identify on which next bridge > "drm_bridge_attach()" on, as it depends on the endpoint the current bridge > has been attached on first, and we don't have that information. > 3) Register more instances of the same chip in DTS, one for each input/output > pair. They gonna share supplies and gpios, and I don't like that. > > I had a quick look at the currently in mainline bridges and none of them has > multiple input endpoints, except for HDMI audio endpoint, which I haven't > found > in use in any DTS. I guess the problem has been already debated and maybe > solved > in the past, so feel free to point me to other sources. I think this is is a step in wrong direction, IMHO. Your previous patchset was quite OK, at least bindings, IMHO. Few things needed only polishing. Here we have unmanaged/transparent bridge, which is totally different, what happened to regulators and gpios from previous iteration. I do not have schematics of the board, but I guess respective pins of the bridge must be connected somehow. I think the problem you want to avoid (double bridge) should not be a problem at all. I suppose the most important is to have correct bindings - as they need to be stable. If you really must to do hacks better is to put them into driver. Regards Andrzej > > Jacopo Mondi (3): > dt-bindings: display: bridge: Document LVDS to parallel decoder > drm: bridge: Add LVDS decoder driver > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle > > .../bindings/display/bridge/lvds-decoder.txt | 42 ++ > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- > drivers/gpu/drm/bridge/Kconfig | 8 ++ > drivers/gpu/drm/bridge/Makefile| 1 + > drivers/gpu/drm/bridge/lvds-decoder.c | 157 > + > 5 files changed, 237 insertions(+), 2 deletions(-) > create mode 100644 > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c > > -- > 2.7.4 > > > >
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hello Archit,
On Sat, Mar 10, 2018 at 11:23:19AM +0530, Archit Taneja wrote:
> Hi,
>
> On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
> >Hello,
> >after some discussion on the proposed bindings for generic lvds decoder
> > and
> >Thine THC63LVD1024, I decided to drop the THC63 specific part and just live
> >with
> >a transparent decoder that does not support any configuration from DT.
> >
> >Dropping THC63 support to avoid discussion on how to better implement support
> >for a DRM bridge with 2 input ports and focus on LVDS mode propagation
> >through
> >bridges as explained in v1 cover letter (for DRM people: please see [1] as
> >why
> >I find difficult to implement support for bridges with multiple input
> >endpoints)
> >
> >Same base branch as v1, with same patches for V3M Eagle applied on top.
> >git://jmondi.org/linux v3m/v4.16-rc3/base
> >
> >Thanks
> >j
> >
> >v1 -> v2:
> >- Drop support for THC63LVD1024
> >
> >[1] I had a quick at how to model a DRM bridge with multiple input
> >ports, and I see a blocker in how DRM identifies and matches bridges using
> >the devices node in place of the endpoint nodes.
> >
> >As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only
> >a few ways to support that:
> > 1) register 2 drm bridges from the same driver (one for each input/output
> > pair)
> > but they would both be matches on the same device node when the
> > preceding
> > bridge calls "of_drm_find_bridge()".
>
> I think this is the way to go. DRM doesn't say anywhere that we can't have 2
> drm_bridge-s contained in a single device. About the issue with
> of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
> the bridge1 and bridge2 nodes as shown below, wouldn't that suffice. From
> what I know, we don't necessarily need to set the bridge's of_node
> to the device (i.e, thschip) itself.
That's fine, but this implies that the preceding bridge (or encoder) in the
DRM pipeline has then to collect the "port" node and match on it
specifically when it attaches this driver. This introduces an ad-hoc
policy that prevents this driver from being easily integrated in
existing pipelines (where bridges are matched on the device node).
Also, I don't know much about the DRM framework, but it seems to me
that the helper function designed to find the next component to attach
to in the DRM pipeline is:
drm_of_find_panel_or_bridge():
remote = of_graph_get_remote_node();
ep = of_graph_get_endpoint_by_regs();
return of_graph_get_remote_port_parent(); <-- This returns the
device node
of_drm_find_panel(remote);
of_drm_find_bridge(remote);
I so dare to say matching on device node is kind of the intended way
to do things in DRM, and this driver with two endpoints that wants to
be matched on port nodes would be kind of special one that does not
work as other driver expects to.
Is my understanding correct, or have I misinterpreted something?
Thanks
j
>
> thschip {
> ...
> ports {
> bridge1: port@0 {
> ...
> };
>
> bridge2: port@1 {
> ...
> };
> };
> };
>
>
> Thanks,
> Archit
>
> > 2) register a single bridge with multiple "next bridges", but when the
> > bridge
> > gets attached I don't see a way on how to identify on which next bridge
> > "drm_bridge_attach()" on, as it depends on the endpoint the current
> > bridge
> > has been attached on first, and we don't have that information.
> > 3) Register more instances of the same chip in DTS, one for each
> > input/output
> > pair. They gonna share supplies and gpios, and I don't like that.
> >
> >I had a quick look at the currently in mainline bridges and none of them has
> >multiple input endpoints, except for HDMI audio endpoint, which I haven't
> >found
> >in use in any DTS. I guess the problem has been already debated and maybe
> >solved
> >in the past, so feel free to point me to other sources.
> >
> >Jacopo Mondi (3):
> > dt-bindings: display: bridge: Document LVDS to parallel decoder
> > drm: bridge: Add LVDS decoder driver
> > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle
> >
> > .../bindings/display/bridge/lvds-decoder.txt | 42 ++
> > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++-
> > drivers/gpu/drm/bridge/Kconfig | 8 ++
> > drivers/gpu/drm/bridge/Makefile| 1 +
> > drivers/gpu/drm/bridge/lvds-decoder.c | 157
> > +
> > 5 files changed, 237 insertions(+), 2 deletions(-)
> > create mode 100644
> > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt
> > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c
> >
> >--
> >2.7.4
> >
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hello Archit,
On Sat, Mar 10, 2018 at 11:23:19AM +0530, Archit Taneja wrote:
> Hi,
>
> On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
> >Hello,
> >after some discussion on the proposed bindings for generic lvds decoder
> > and
> >Thine THC63LVD1024, I decided to drop the THC63 specific part and just live
> >with
> >a transparent decoder that does not support any configuration from DT.
> >
> >Dropping THC63 support to avoid discussion on how to better implement support
> >for a DRM bridge with 2 input ports and focus on LVDS mode propagation
> >through
> >bridges as explained in v1 cover letter (for DRM people: please see [1] as
> >why
> >I find difficult to implement support for bridges with multiple input
> >endpoints)
> >
> >Same base branch as v1, with same patches for V3M Eagle applied on top.
> >git://jmondi.org/linux v3m/v4.16-rc3/base
> >
> >Thanks
> >j
> >
> >v1 -> v2:
> >- Drop support for THC63LVD1024
> >
> >[1] I had a quick at how to model a DRM bridge with multiple input
> >ports, and I see a blocker in how DRM identifies and matches bridges using
> >the devices node in place of the endpoint nodes.
> >
> >As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only
> >a few ways to support that:
> > 1) register 2 drm bridges from the same driver (one for each input/output
> > pair)
> > but they would both be matches on the same device node when the
> > preceding
> > bridge calls "of_drm_find_bridge()".
>
> I think this is the way to go. DRM doesn't say anywhere that we can't have 2
> drm_bridge-s contained in a single device. About the issue with
> of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
> the bridge1 and bridge2 nodes as shown below, wouldn't that suffice. From
> what I know, we don't necessarily need to set the bridge's of_node
> to the device (i.e, thschip) itself.
That's fine, but this implies that the preceding bridge (or encoder) in the
DRM pipeline has then to collect the "port" node and match on it
specifically when it attaches this driver. This introduces an ad-hoc
policy that prevents this driver from being easily integrated in
existing pipelines (where bridges are matched on the device node).
Also, I don't know much about the DRM framework, but it seems to me
that the helper function designed to find the next component to attach
to in the DRM pipeline is:
drm_of_find_panel_or_bridge():
remote = of_graph_get_remote_node();
ep = of_graph_get_endpoint_by_regs();
return of_graph_get_remote_port_parent(); <-- This returns the
device node
of_drm_find_panel(remote);
of_drm_find_bridge(remote);
I so dare to say matching on device node is kind of the intended way
to do things in DRM, and this driver with two endpoints that wants to
be matched on port nodes would be kind of special one that does not
work as other driver expects to.
Is my understanding correct, or have I misinterpreted something?
Thanks
j
>
> thschip {
> ...
> ports {
> bridge1: port@0 {
> ...
> };
>
> bridge2: port@1 {
> ...
> };
> };
> };
>
>
> Thanks,
> Archit
>
> > 2) register a single bridge with multiple "next bridges", but when the
> > bridge
> > gets attached I don't see a way on how to identify on which next bridge
> > "drm_bridge_attach()" on, as it depends on the endpoint the current
> > bridge
> > has been attached on first, and we don't have that information.
> > 3) Register more instances of the same chip in DTS, one for each
> > input/output
> > pair. They gonna share supplies and gpios, and I don't like that.
> >
> >I had a quick look at the currently in mainline bridges and none of them has
> >multiple input endpoints, except for HDMI audio endpoint, which I haven't
> >found
> >in use in any DTS. I guess the problem has been already debated and maybe
> >solved
> >in the past, so feel free to point me to other sources.
> >
> >Jacopo Mondi (3):
> > dt-bindings: display: bridge: Document LVDS to parallel decoder
> > drm: bridge: Add LVDS decoder driver
> > arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle
> >
> > .../bindings/display/bridge/lvds-decoder.txt | 42 ++
> > arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++-
> > drivers/gpu/drm/bridge/Kconfig | 8 ++
> > drivers/gpu/drm/bridge/Makefile| 1 +
> > drivers/gpu/drm/bridge/lvds-decoder.c | 157
> > +
> > 5 files changed, 237 insertions(+), 2 deletions(-)
> > create mode 100644
> > Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt
> > create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c
> >
> >--
> >2.7.4
> >
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi,
On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
Hello,
after some discussion on the proposed bindings for generic lvds decoder and
Thine THC63LVD1024, I decided to drop the THC63 specific part and just live with
a transparent decoder that does not support any configuration from DT.
Dropping THC63 support to avoid discussion on how to better implement support
for a DRM bridge with 2 input ports and focus on LVDS mode propagation through
bridges as explained in v1 cover letter (for DRM people: please see [1] as why
I find difficult to implement support for bridges with multiple input endpoints)
Same base branch as v1, with same patches for V3M Eagle applied on top.
git://jmondi.org/linux v3m/v4.16-rc3/base
Thanks
j
v1 -> v2:
- Drop support for THC63LVD1024
[1] I had a quick at how to model a DRM bridge with multiple input
ports, and I see a blocker in how DRM identifies and matches bridges using
the devices node in place of the endpoint nodes.
As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only
a few ways to support that:
1) register 2 drm bridges from the same driver (one for each input/output
pair)
but they would both be matches on the same device node when the preceding
bridge calls "of_drm_find_bridge()".
I think this is the way to go. DRM doesn't say anywhere that we can't
have 2 drm_bridge-s contained in a single device. About the issue with
of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
the bridge1 and bridge2 nodes as shown below, wouldn't that suffice.
From what I know, we don't necessarily need to set the bridge's of_node
to the device (i.e, thschip) itself.
thschip {
...
ports {
bridge1: port@0 {
...
};
bridge2: port@1 {
...
};
};
};
Thanks,
Archit
2) register a single bridge with multiple "next bridges", but when the bridge
gets attached I don't see a way on how to identify on which next bridge
"drm_bridge_attach()" on, as it depends on the endpoint the current bridge
has been attached on first, and we don't have that information.
3) Register more instances of the same chip in DTS, one for each input/output
pair. They gonna share supplies and gpios, and I don't like that.
I had a quick look at the currently in mainline bridges and none of them has
multiple input endpoints, except for HDMI audio endpoint, which I haven't found
in use in any DTS. I guess the problem has been already debated and maybe solved
in the past, so feel free to point me to other sources.
Jacopo Mondi (3):
dt-bindings: display: bridge: Document LVDS to parallel decoder
drm: bridge: Add LVDS decoder driver
arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle
.../bindings/display/bridge/lvds-decoder.txt | 42 ++
arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++-
drivers/gpu/drm/bridge/Kconfig | 8 ++
drivers/gpu/drm/bridge/Makefile| 1 +
drivers/gpu/drm/bridge/lvds-decoder.c | 157 +
5 files changed, 237 insertions(+), 2 deletions(-)
create mode 100644
Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt
create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c
--
2.7.4
Re: [PATCH v2 0/3] drm: Add LVDS decoder bridge
Hi,
On Friday 09 March 2018 07:21 PM, Jacopo Mondi wrote:
Hello,
after some discussion on the proposed bindings for generic lvds decoder and
Thine THC63LVD1024, I decided to drop the THC63 specific part and just live with
a transparent decoder that does not support any configuration from DT.
Dropping THC63 support to avoid discussion on how to better implement support
for a DRM bridge with 2 input ports and focus on LVDS mode propagation through
bridges as explained in v1 cover letter (for DRM people: please see [1] as why
I find difficult to implement support for bridges with multiple input endpoints)
Same base branch as v1, with same patches for V3M Eagle applied on top.
git://jmondi.org/linux v3m/v4.16-rc3/base
Thanks
j
v1 -> v2:
- Drop support for THC63LVD1024
[1] I had a quick at how to model a DRM bridge with multiple input
ports, and I see a blocker in how DRM identifies and matches bridges using
the devices node in place of the endpoint nodes.
As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only
a few ways to support that:
1) register 2 drm bridges from the same driver (one for each input/output
pair)
but they would both be matches on the same device node when the preceding
bridge calls "of_drm_find_bridge()".
I think this is the way to go. DRM doesn't say anywhere that we can't
have 2 drm_bridge-s contained in a single device. About the issue with
of_drm_find_bridge(), if you set the 2 bridge's 'of_node' field to
the bridge1 and bridge2 nodes as shown below, wouldn't that suffice.
From what I know, we don't necessarily need to set the bridge's of_node
to the device (i.e, thschip) itself.
thschip {
...
ports {
bridge1: port@0 {
...
};
bridge2: port@1 {
...
};
};
};
Thanks,
Archit
2) register a single bridge with multiple "next bridges", but when the bridge
gets attached I don't see a way on how to identify on which next bridge
"drm_bridge_attach()" on, as it depends on the endpoint the current bridge
has been attached on first, and we don't have that information.
3) Register more instances of the same chip in DTS, one for each input/output
pair. They gonna share supplies and gpios, and I don't like that.
I had a quick look at the currently in mainline bridges and none of them has
multiple input endpoints, except for HDMI audio endpoint, which I haven't found
in use in any DTS. I guess the problem has been already debated and maybe solved
in the past, so feel free to point me to other sources.
Jacopo Mondi (3):
dt-bindings: display: bridge: Document LVDS to parallel decoder
drm: bridge: Add LVDS decoder driver
arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle
.../bindings/display/bridge/lvds-decoder.txt | 42 ++
arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++-
drivers/gpu/drm/bridge/Kconfig | 8 ++
drivers/gpu/drm/bridge/Makefile| 1 +
drivers/gpu/drm/bridge/lvds-decoder.c | 157 +
5 files changed, 237 insertions(+), 2 deletions(-)
create mode 100644
Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt
create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c
--
2.7.4
[PATCH v2 0/3] drm: Add LVDS decoder bridge
Hello, after some discussion on the proposed bindings for generic lvds decoder and Thine THC63LVD1024, I decided to drop the THC63 specific part and just live with a transparent decoder that does not support any configuration from DT. Dropping THC63 support to avoid discussion on how to better implement support for a DRM bridge with 2 input ports and focus on LVDS mode propagation through bridges as explained in v1 cover letter (for DRM people: please see [1] as why I find difficult to implement support for bridges with multiple input endpoints) Same base branch as v1, with same patches for V3M Eagle applied on top. git://jmondi.org/linux v3m/v4.16-rc3/base Thanks j v1 -> v2: - Drop support for THC63LVD1024 [1] I had a quick at how to model a DRM bridge with multiple input ports, and I see a blocker in how DRM identifies and matches bridges using the devices node in place of the endpoint nodes. As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only a few ways to support that: 1) register 2 drm bridges from the same driver (one for each input/output pair) but they would both be matches on the same device node when the preceding bridge calls "of_drm_find_bridge()". 2) register a single bridge with multiple "next bridges", but when the bridge gets attached I don't see a way on how to identify on which next bridge "drm_bridge_attach()" on, as it depends on the endpoint the current bridge has been attached on first, and we don't have that information. 3) Register more instances of the same chip in DTS, one for each input/output pair. They gonna share supplies and gpios, and I don't like that. I had a quick look at the currently in mainline bridges and none of them has multiple input endpoints, except for HDMI audio endpoint, which I haven't found in use in any DTS. I guess the problem has been already debated and maybe solved in the past, so feel free to point me to other sources. Jacopo Mondi (3): dt-bindings: display: bridge: Document LVDS to parallel decoder drm: bridge: Add LVDS decoder driver arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle .../bindings/display/bridge/lvds-decoder.txt | 42 ++ arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- drivers/gpu/drm/bridge/Kconfig | 8 ++ drivers/gpu/drm/bridge/Makefile| 1 + drivers/gpu/drm/bridge/lvds-decoder.c | 157 + 5 files changed, 237 insertions(+), 2 deletions(-) create mode 100644 Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c -- 2.7.4
[PATCH v2 0/3] drm: Add LVDS decoder bridge
Hello, after some discussion on the proposed bindings for generic lvds decoder and Thine THC63LVD1024, I decided to drop the THC63 specific part and just live with a transparent decoder that does not support any configuration from DT. Dropping THC63 support to avoid discussion on how to better implement support for a DRM bridge with 2 input ports and focus on LVDS mode propagation through bridges as explained in v1 cover letter (for DRM people: please see [1] as why I find difficult to implement support for bridges with multiple input endpoints) Same base branch as v1, with same patches for V3M Eagle applied on top. git://jmondi.org/linux v3m/v4.16-rc3/base Thanks j v1 -> v2: - Drop support for THC63LVD1024 [1] I had a quick at how to model a DRM bridge with multiple input ports, and I see a blocker in how DRM identifies and matches bridges using the devices node in place of the endpoint nodes. As THC63LVD1024 supports up to 2 LVDS inputs and 2 LVDS outputs, I see only a few ways to support that: 1) register 2 drm bridges from the same driver (one for each input/output pair) but they would both be matches on the same device node when the preceding bridge calls "of_drm_find_bridge()". 2) register a single bridge with multiple "next bridges", but when the bridge gets attached I don't see a way on how to identify on which next bridge "drm_bridge_attach()" on, as it depends on the endpoint the current bridge has been attached on first, and we don't have that information. 3) Register more instances of the same chip in DTS, one for each input/output pair. They gonna share supplies and gpios, and I don't like that. I had a quick look at the currently in mainline bridges and none of them has multiple input endpoints, except for HDMI audio endpoint, which I haven't found in use in any DTS. I guess the problem has been already debated and maybe solved in the past, so feel free to point me to other sources. Jacopo Mondi (3): dt-bindings: display: bridge: Document LVDS to parallel decoder drm: bridge: Add LVDS decoder driver arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle .../bindings/display/bridge/lvds-decoder.txt | 42 ++ arch/arm64/boot/dts/renesas/r8a77970-eagle.dts | 31 +++- drivers/gpu/drm/bridge/Kconfig | 8 ++ drivers/gpu/drm/bridge/Makefile| 1 + drivers/gpu/drm/bridge/lvds-decoder.c | 157 + 5 files changed, 237 insertions(+), 2 deletions(-) create mode 100644 Documentation/devicetree/bindings/display/bridge/lvds-decoder.txt create mode 100644 drivers/gpu/drm/bridge/lvds-decoder.c -- 2.7.4
