Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
I'm a bit late to the game but I don't think this is merged
yet.
On 2024-01-15 11:05, Andri Yngvason wrote:
> From: Werner Sembach
>
> Add a new general drm property "force color format" which can be used
> by userspace to tell the graphics driver which color format to use.
>
> Possible options are:
> - auto (default/current behaviour)
> - rgb
> - ycbcr444
> - ycbcr422 (supported by neither amdgpu or i915)
If no driver uses this should we expose this now? I would
prefer to leave ycbcr422 out of this until we have a driver
that actually uses it.
I've seen too many properties with ever possible value defined
but they're not used by any (open) userspace and then become
the object of intense discussion on how they should work. I
doubt that this would happen here, but I still feel a slight
aversion to defining things that no open userspace can use at
this point.
I agree with all of Sebastian and Pekka's comments elsewhere in
this thread, in particular with Sebastian's comments to not
advertise color formats that a driver can't support. See this
patch for how I implemented something similar for Colorspace
c265f340eaa8 ("drm/connector: Allow drivers to pass list of supported
colorspaces")
Harry
> - ycbcr420
>
> In theory the auto option should choose the best available option for the
> current setup, but because of bad internal conversion some monitors look
> better with rgb and some with ycbcr444.
>
> Also, because of bad shielded connectors and/or cables, it might be
> preferable to use the less bandwidth heavy ycbcr422 and ycbcr420 formats
> for a signal that is less susceptible to interference.
>
> In the future, automatic color calibration for screens might also depend on
> this option being available.
>
> Signed-off-by: Werner Sembach
> Signed-off-by: Andri Yngvason
> Tested-by: Andri Yngvason
> ---
>
> Changes in v2:
> - Renamed to "force color format" from "preferred color format"
> - Removed Reported-by pointing to invalid email address
>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 4 +++
> drivers/gpu/drm/drm_atomic_uapi.c | 4 +++
> drivers/gpu/drm/drm_connector.c | 48 +
> include/drm/drm_connector.h | 16 ++
> 4 files changed, 72 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c
> index 39ef0a6addeba..1dabd164c4f09 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -707,6 +707,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> if (old_connector_state->max_requested_bpc !=
> new_connector_state->max_requested_bpc)
> new_crtc_state->connectors_changed = true;
> +
> + if (old_connector_state->force_color_format !=
> + new_connector_state->force_color_format)
> + new_crtc_state->connectors_changed = true;
> }
>
> if (funcs->atomic_check)
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
> b/drivers/gpu/drm/drm_atomic_uapi.c
> index 29d4940188d49..e45949bf4615f 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -776,6 +776,8 @@ static int drm_atomic_connector_set_property(struct
> drm_connector *connector,
> state->max_requested_bpc = val;
> } else if (property == connector->privacy_screen_sw_state_property) {
> state->privacy_screen_sw_state = val;
> + } else if (property == connector->force_color_format_property) {
> + state->force_color_format = val;
> } else if (connector->funcs->atomic_set_property) {
> return connector->funcs->atomic_set_property(connector,
> state, property, val);
> @@ -859,6 +861,8 @@ drm_atomic_connector_get_property(struct drm_connector
> *connector,
> *val = state->max_requested_bpc;
> } else if (property == connector->privacy_screen_sw_state_property) {
> *val = state->privacy_screen_sw_state;
> + } else if (property == connector->force_color_format_property) {
> + *val = state->force_color_format;
> } else if (connector->funcs->atomic_get_property) {
> return connector->funcs->atomic_get_property(connector,
> state, property, val);
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index b0516505f7ae9..e0535e58b4535 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1061,6 +1061,14 @@ static const struct drm_prop_enum_list
> drm_dp_subconnector_enum_list[] = {
> { DRM_MODE_SUBCONNECTOR_Native, "Native"}, /* DP */
> };
>
> +static const struct drm_prop_enum_list drm_force_color_format_enum_list[] = {
> + { 0, "auto" },
> + {
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
On Wed, 17 Jan 2024 12:58:15 + Andri Yngvason wrote: > mið., 17. jan. 2024 kl. 09:21 skrifaði Pekka Paalanen : ... > > EDID and DisplayID standards also evolve. The kernel could be behind > > userspace in chasing them, which was the reason why the kernel does not > > validate HDR_OUTPUT_METADATA against EDID. > > > > The design of today with HDR_OUTPUT_METADATA and whatnot is > > that userspace is responsible for checking sink capabilities, and > > atomic check is responsible for driver and display controller > > capabilities. > > I'm not really sure where you're going with this. Are you for or > against userspace parsing EDID instead of getting the information from > the kernel? In that specific email, neither. I attempted to describe the current situation without any bias towards whether I think that is a good or not design. There is an existing behaviour, and if you want to deviate from that, you need more justification than for following it. Even the video modes list that I mentioned as the major example of things that userspace should not parse from EDID itself is not exhaustive nor exclusive. Userspace can still craft an arbitrary video mode and set it. If the driver and display controller can do it, it passes I believe, even if it would literally destroy the sink (in the CRT era, you could burn the flyback transistor of an unfortunate monitor). If you want me to take a stance, I think the kernel not gating settings based on EDID for these things is a good idea for these reasons: - EDID can easily be wrong, and it is easier to test sink "unsupported" configurations if you do not need to craft a modified EDID and (reboot to?) load it in the kernel first. - EDID spec gets occasionally extended. If the kernel gated settings, you would not be able to test new features without getting an updated kernel that allows them to pass. This mostly applies to blob properties, and not enums, because you cannot set arbitrary values to enum properties. Finally, as to why userspace parsing EDID at all is a good idea: - The kernel is not interested in most of the stuff contained in EDIDs, so it has no inherent reason to parse everything. - EDID is a fairly wide "API" and gets occasionally extended. Replicating all that in a kernel UAPI is a lot of work that won't benefit the kernel itself. There does not seem to be benefit in reinventing EDID information encoding in fine-grained UAPI structures, but there certainly is risk, because UAPI is written in stone once published. Userspace can get the equivalent from libraries like libdisplay-info which are much easier to develop and replace than UAPI. Thanks, pq pgpbVt0gQciYB.pgp Description: OpenPGP digital signature
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
On Wed, Jan 17, 2024 at 12:58:15PM +, Andri Yngvason wrote: > mið., 17. jan. 2024 kl. 09:21 skrifaði Pekka Paalanen : > > > > On Tue, 16 Jan 2024 14:11:43 + > > Andri Yngvason wrote: > > > > > þri., 16. jan. 2024 kl. 13:29 skrifaði Sebastian Wick > > > : > > > > > > > > On Tue, Jan 16, 2024 at 01:13:13PM +, Andri Yngvason wrote: > > > [...] > > > > > şri., 16. jan. 2024 kl. 11:42 skrifaği Sebastian Wick > > > > > : > > > > > > > > > > > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > > > > > > From: Werner Sembach > > > > > > > > > > > > > > Add a new general drm property "force color format" which can be > > > > > > > used > > > > > > > by userspace to tell the graphics driver which color format to > > > > > > > use. > > > > > > > > > > > > I don't like the "force" in the name. This just selects the color > > > > > > format, let's just call it "color format" then. > > > > > > > > > > > > > > > > In previous revisions, this was "preferred color format" and "actual > > > > > color format", of which the latter has been dropped. I recommend > > > > > reading the discussion for previous revisions. > > > > > > > > Please don't imply that I didn't read the thread I'm answering to. > > > > FYI, I have not read this thread. > > > > pq, You did not read this summary? > https://lore.kernel.org/dri-devel/cafnqbqwjejax6b4oewpgasmud5_nxzymxufdog294ctvgbt...@mail.gmail.com/ > > You partook in the discussion on IRC. Please read it and tell me if I > misunderstood anything. > > Sebastian, I apologise. You clearly read it as you even replied to it! Thank you :) > > > > > > > > > There are arguments for adding "actual color format" later and if it > > > > > is added later, we'd end up with "color format" and "actual color > > > > > format", which might be confusing, and it is why I chose to call it > > > > > "force color format" because it clearly communicates intent and > > > > > disambiguates it from "actual color format". > > > > > > > > There is no such thing as "actual color format" in upstream though. > > > > Basing your naming on discarded ideas is not useful. The thing that sets > > > > the color space for example is called "Colorspace", not "force > > > > colorspace". > > > > > > > > > > Sure, I'm happy with calling it whatever people want. Maybe we can > > > have a vote on it? > > > > It would sound strange to say "force color format" = "auto". Just drop > > the "force" of it. > > > > If and when we need the feedback counterpart, it could be an immutable > > prop called "active color format" where "auto" is not a valid value, or > > something in the new "output properties" design Sima has been thinking > > of. > > There seems to be consensus for calling it "color format" > > > > > > > > [...] > > > > > > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > > > > > > * drm_connector_attach_max_bpc_property() to create and > > > > > > > attach the > > > > > > > * property to the connector during initialization. > > > > > > > * > > > > > > > + * force color format: > > > > > > > + * This property is used by userspace to change the used color > > > > > > > format. When > > > > > > > + * used the driver will use the selected format if valid for > > > > > > > the hardware, > > > > > > > > > > > > All properties are always "used", they just can have different > > > > > > values. > > > > > > You probably want to talk about the auto mode here. > > > > > > > > > > Maybe we can say something like: If userspace does not set the > > > > > property or if it is explicitly set to zero, the driver will select > > > > > the appropriate color format based on other constraints. > > > > > > > > The property can be in any state without involvement from user space. > > > > Don't talk about setting it, talk about the state it is in: > > > > > > > > When the color format is auto, the driver will select a format. > > > > > > > > > > Ok. > > > > > > > > > > > > > > > > + * sink, and current resolution and refresh rate combination. > > > > > > > Drivers to > > > > > > > > > > > > If valid? So when a value is not actually supported user space can > > > > > > still > > > > > > set it? What happens then? How should user space figure out if the > > > > > > driver and the sink support the format? > > > > > > > > > > The kernel does not expose this property unless it's implemented in > > > > > the driver. > > > > > > > > If the driver simply doesn't support *one format*, the enum value for > > > > that format should not be exposed, period. This isn't about the property > > > > on its own. > > > > > > Right, understood. You mean that enum should only contain values that > > > are supported by the driver. > > > > Yes. When a driver installs a property, it can choose which of the enum > > entries are exposed. That cannot be changed later though, so the list > > cannot live by the currently connected sink, only by what the driver > > and display controlled could ever do.
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
mið., 17. jan. 2024 kl. 09:21 skrifaði Pekka Paalanen : > > On Tue, 16 Jan 2024 14:11:43 + > Andri Yngvason wrote: > > > þri., 16. jan. 2024 kl. 13:29 skrifaði Sebastian Wick > > : > > > > > > On Tue, Jan 16, 2024 at 01:13:13PM +, Andri Yngvason wrote: > > [...] > > > > şri., 16. jan. 2024 kl. 11:42 skrifaği Sebastian Wick > > > > : > > > > > > > > > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > > > > > From: Werner Sembach > > > > > > > > > > > > Add a new general drm property "force color format" which can be > > > > > > used > > > > > > by userspace to tell the graphics driver which color format to use. > > > > > > > > > > I don't like the "force" in the name. This just selects the color > > > > > format, let's just call it "color format" then. > > > > > > > > > > > > > In previous revisions, this was "preferred color format" and "actual > > > > color format", of which the latter has been dropped. I recommend > > > > reading the discussion for previous revisions. > > > > > > Please don't imply that I didn't read the thread I'm answering to. > > FYI, I have not read this thread. > pq, You did not read this summary? https://lore.kernel.org/dri-devel/cafnqbqwjejax6b4oewpgasmud5_nxzymxufdog294ctvgbt...@mail.gmail.com/ You partook in the discussion on IRC. Please read it and tell me if I misunderstood anything. Sebastian, I apologise. You clearly read it as you even replied to it! > > > > > > > There are arguments for adding "actual color format" later and if it > > > > is added later, we'd end up with "color format" and "actual color > > > > format", which might be confusing, and it is why I chose to call it > > > > "force color format" because it clearly communicates intent and > > > > disambiguates it from "actual color format". > > > > > > There is no such thing as "actual color format" in upstream though. > > > Basing your naming on discarded ideas is not useful. The thing that sets > > > the color space for example is called "Colorspace", not "force > > > colorspace". > > > > > > > Sure, I'm happy with calling it whatever people want. Maybe we can > > have a vote on it? > > It would sound strange to say "force color format" = "auto". Just drop > the "force" of it. > > If and when we need the feedback counterpart, it could be an immutable > prop called "active color format" where "auto" is not a valid value, or > something in the new "output properties" design Sima has been thinking > of. There seems to be consensus for calling it "color format" > > > > > [...] > > > > > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > > > > > * drm_connector_attach_max_bpc_property() to create and attach > > > > > > the > > > > > > * property to the connector during initialization. > > > > > > * > > > > > > + * force color format: > > > > > > + * This property is used by userspace to change the used color > > > > > > format. When > > > > > > + * used the driver will use the selected format if valid for the > > > > > > hardware, > > > > > > > > > > All properties are always "used", they just can have different values. > > > > > You probably want to talk about the auto mode here. > > > > > > > > Maybe we can say something like: If userspace does not set the > > > > property or if it is explicitly set to zero, the driver will select > > > > the appropriate color format based on other constraints. > > > > > > The property can be in any state without involvement from user space. > > > Don't talk about setting it, talk about the state it is in: > > > > > > When the color format is auto, the driver will select a format. > > > > > > > Ok. > > > > > > > > > > > > > + * sink, and current resolution and refresh rate combination. > > > > > > Drivers to > > > > > > > > > > If valid? So when a value is not actually supported user space can > > > > > still > > > > > set it? What happens then? How should user space figure out if the > > > > > driver and the sink support the format? > > > > > > > > The kernel does not expose this property unless it's implemented in the > > > > driver. > > > > > > If the driver simply doesn't support *one format*, the enum value for > > > that format should not be exposed, period. This isn't about the property > > > on its own. > > > > Right, understood. You mean that enum should only contain values that > > are supported by the driver. > > Yes. When a driver installs a property, it can choose which of the enum > entries are exposed. That cannot be changed later though, so the list > cannot live by the currently connected sink, only by what the driver > and display controlled could ever do. Yes, and I think that basing it also on the connected sink's capabilities would just add complexity for very little gain. In fact, I think that limiting it based on the driver's capabilities is also over-engineering, but I don't mind adding it if that's what people really want. > > > > > This was originally "preferred color format".
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
On Tue, 16 Jan 2024 14:11:43 + Andri Yngvason wrote: > þri., 16. jan. 2024 kl. 13:29 skrifaði Sebastian Wick > : > > > > On Tue, Jan 16, 2024 at 01:13:13PM +, Andri Yngvason wrote: > [...] > > > şri., 16. jan. 2024 kl. 11:42 skrifaği Sebastian Wick > > > : > > > > > > > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > > > > From: Werner Sembach > > > > > > > > > > Add a new general drm property "force color format" which can be used > > > > > by userspace to tell the graphics driver which color format to use. > > > > > > > > I don't like the "force" in the name. This just selects the color > > > > format, let's just call it "color format" then. > > > > > > > > > > In previous revisions, this was "preferred color format" and "actual > > > color format", of which the latter has been dropped. I recommend > > > reading the discussion for previous revisions. > > > > Please don't imply that I didn't read the thread I'm answering to. FYI, I have not read this thread. > > > > > There are arguments for adding "actual color format" later and if it > > > is added later, we'd end up with "color format" and "actual color > > > format", which might be confusing, and it is why I chose to call it > > > "force color format" because it clearly communicates intent and > > > disambiguates it from "actual color format". > > > > There is no such thing as "actual color format" in upstream though. > > Basing your naming on discarded ideas is not useful. The thing that sets > > the color space for example is called "Colorspace", not "force > > colorspace". > > > > Sure, I'm happy with calling it whatever people want. Maybe we can > have a vote on it? It would sound strange to say "force color format" = "auto". Just drop the "force" of it. If and when we need the feedback counterpart, it could be an immutable prop called "active color format" where "auto" is not a valid value, or something in the new "output properties" design Sima has been thinking of. > > > [...] > > > > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > > > > * drm_connector_attach_max_bpc_property() to create and attach the > > > > > * property to the connector during initialization. > > > > > * > > > > > + * force color format: > > > > > + * This property is used by userspace to change the used color > > > > > format. When > > > > > + * used the driver will use the selected format if valid for the > > > > > hardware, > > > > > > > > All properties are always "used", they just can have different values. > > > > You probably want to talk about the auto mode here. > > > > > > Maybe we can say something like: If userspace does not set the > > > property or if it is explicitly set to zero, the driver will select > > > the appropriate color format based on other constraints. > > > > The property can be in any state without involvement from user space. > > Don't talk about setting it, talk about the state it is in: > > > > When the color format is auto, the driver will select a format. > > > > Ok. > > > > > > > > > > + * sink, and current resolution and refresh rate combination. > > > > > Drivers to > > > > > > > > If valid? So when a value is not actually supported user space can still > > > > set it? What happens then? How should user space figure out if the > > > > driver and the sink support the format? > > > > > > The kernel does not expose this property unless it's implemented in the > > > driver. > > > > If the driver simply doesn't support *one format*, the enum value for > > that format should not be exposed, period. This isn't about the property > > on its own. > > Right, understood. You mean that enum should only contain values that > are supported by the driver. Yes. When a driver installs a property, it can choose which of the enum entries are exposed. That cannot be changed later though, so the list cannot live by the currently connected sink, only by what the driver and display controlled could ever do. > > > This was originally "preferred color format". Perhaps the > > > documentation should better reflect that it is now a mandatory > > > constraint which fails the modeset if not satisfied. > > > > That would definitely help. > > > > > > > > > > For the Colorspace prop, the kernel just exposes all formats it supports > > > > (independent of the sink) and then makes it the job of user space to > > > > figure out if the sink supports it. > > > > > > > > The same could be done here. Property value is exposed if the driver > > > > supports it in general, commits can fail if the driver can't support it > > > > for a specific commit because e.g. the resolution or refresh rate. User > > > > space must look at the EDID/DisplayID/mode to figure out the supported > > > > format for the sink. > > > > > > Yes, we can make it possible for userspace to discover which modes are > > > supported by the monitor, but there are other constraints that
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
þri., 16. jan. 2024 kl. 13:29 skrifaði Sebastian Wick : > > On Tue, Jan 16, 2024 at 01:13:13PM +, Andri Yngvason wrote: [...] > > şri., 16. jan. 2024 kl. 11:42 skrifaği Sebastian Wick > > : > > > > > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > > > From: Werner Sembach > > > > > > > > Add a new general drm property "force color format" which can be used > > > > by userspace to tell the graphics driver which color format to use. > > > > > > I don't like the "force" in the name. This just selects the color > > > format, let's just call it "color format" then. > > > > > > > In previous revisions, this was "preferred color format" and "actual > > color format", of which the latter has been dropped. I recommend > > reading the discussion for previous revisions. > > Please don't imply that I didn't read the thread I'm answering to. > > > There are arguments for adding "actual color format" later and if it > > is added later, we'd end up with "color format" and "actual color > > format", which might be confusing, and it is why I chose to call it > > "force color format" because it clearly communicates intent and > > disambiguates it from "actual color format". > > There is no such thing as "actual color format" in upstream though. > Basing your naming on discarded ideas is not useful. The thing that sets > the color space for example is called "Colorspace", not "force > colorspace". > Sure, I'm happy with calling it whatever people want. Maybe we can have a vote on it? > > [...] > > > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > > > * drm_connector_attach_max_bpc_property() to create and attach the > > > > * property to the connector during initialization. > > > > * > > > > + * force color format: > > > > + * This property is used by userspace to change the used color > > > > format. When > > > > + * used the driver will use the selected format if valid for the > > > > hardware, > > > > > > All properties are always "used", they just can have different values. > > > You probably want to talk about the auto mode here. > > > > Maybe we can say something like: If userspace does not set the > > property or if it is explicitly set to zero, the driver will select > > the appropriate color format based on other constraints. > > The property can be in any state without involvement from user space. > Don't talk about setting it, talk about the state it is in: > > When the color format is auto, the driver will select a format. > Ok. > > > > > > > + * sink, and current resolution and refresh rate combination. > > > > Drivers to > > > > > > If valid? So when a value is not actually supported user space can still > > > set it? What happens then? How should user space figure out if the > > > driver and the sink support the format? > > > > The kernel does not expose this property unless it's implemented in the > > driver. > > If the driver simply doesn't support *one format*, the enum value for > that format should not be exposed, period. This isn't about the property > on its own. Right, understood. You mean that enum should only contain values that are supported by the driver. > > > This was originally "preferred color format". Perhaps the > > documentation should better reflect that it is now a mandatory > > constraint which fails the modeset if not satisfied. > > That would definitely help. > > > > > > > For the Colorspace prop, the kernel just exposes all formats it supports > > > (independent of the sink) and then makes it the job of user space to > > > figure out if the sink supports it. > > > > > > The same could be done here. Property value is exposed if the driver > > > supports it in general, commits can fail if the driver can't support it > > > for a specific commit because e.g. the resolution or refresh rate. User > > > space must look at the EDID/DisplayID/mode to figure out the supported > > > format for the sink. > > > > Yes, we can make it possible for userspace to discover which modes are > > supported by the monitor, but there are other constraints that need to > > be satisfied. This was discussed in the previous revision. > > I mean, yes, that's what I said. User space would then only be > responsible for checking the sink capabilities and the atomic check > would take into account other (non-sink) constraints. Since we need to probe using TEST_ONLY anyway, we'll end up with two mechanisms to do the same thing where one of them depends on the other for completeness. > > > In any case, these things can be added later and need not be a part of > > this change set. > > No, this is the contract between the kernel and user space and has to be > figured out before we can merge new uAPI. > > > > > [...] > > Thanks, Andri
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
On Tue, Jan 16, 2024 at 01:13:13PM +, Andri Yngvason wrote: > Hi Sebastian, > > þri., 16. jan. 2024 kl. 11:42 skrifaði Sebastian Wick > : > > > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > > From: Werner Sembach > > > > > > Add a new general drm property "force color format" which can be used > > > by userspace to tell the graphics driver which color format to use. > > > > I don't like the "force" in the name. This just selects the color > > format, let's just call it "color format" then. > > > > In previous revisions, this was "preferred color format" and "actual > color format", of which the latter has been dropped. I recommend > reading the discussion for previous revisions. Please don't imply that I didn't read the thread I'm answering to. > There are arguments for adding "actual color format" later and if it > is added later, we'd end up with "color format" and "actual color > format", which might be confusing, and it is why I chose to call it > "force color format" because it clearly communicates intent and > disambiguates it from "actual color format". There is no such thing as "actual color format" in upstream though. Basing your naming on discarded ideas is not useful. The thing that sets the color space for example is called "Colorspace", not "force colorspace". > [...] > > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > > * drm_connector_attach_max_bpc_property() to create and attach the > > > * property to the connector during initialization. > > > * > > > + * force color format: > > > + * This property is used by userspace to change the used color format. > > > When > > > + * used the driver will use the selected format if valid for the > > > hardware, > > > > All properties are always "used", they just can have different values. > > You probably want to talk about the auto mode here. > > Maybe we can say something like: If userspace does not set the > property or if it is explicitly set to zero, the driver will select > the appropriate color format based on other constraints. The property can be in any state without involvement from user space. Don't talk about setting it, talk about the state it is in: When the color format is auto, the driver will select a format. > > > > > + * sink, and current resolution and refresh rate combination. Drivers > > > to > > > > If valid? So when a value is not actually supported user space can still > > set it? What happens then? How should user space figure out if the > > driver and the sink support the format? > > The kernel does not expose this property unless it's implemented in the > driver. If the driver simply doesn't support *one format*, the enum value for that format should not be exposed, period. This isn't about the property on its own. > This was originally "preferred color format". Perhaps the > documentation should better reflect that it is now a mandatory > constraint which fails the modeset if not satisfied. That would definitely help. > > > > For the Colorspace prop, the kernel just exposes all formats it supports > > (independent of the sink) and then makes it the job of user space to > > figure out if the sink supports it. > > > > The same could be done here. Property value is exposed if the driver > > supports it in general, commits can fail if the driver can't support it > > for a specific commit because e.g. the resolution or refresh rate. User > > space must look at the EDID/DisplayID/mode to figure out the supported > > format for the sink. > > Yes, we can make it possible for userspace to discover which modes are > supported by the monitor, but there are other constraints that need to > be satisfied. This was discussed in the previous revision. I mean, yes, that's what I said. User space would then only be responsible for checking the sink capabilities and the atomic check would take into account other (non-sink) constraints. > In any case, these things can be added later and need not be a part of > this change set. No, this is the contract between the kernel and user space and has to be figured out before we can merge new uAPI. > > [...] > > Regards, > Andri >
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
Hi Sebastian, þri., 16. jan. 2024 kl. 11:42 skrifaði Sebastian Wick : > > On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote: > > From: Werner Sembach > > > > Add a new general drm property "force color format" which can be used > > by userspace to tell the graphics driver which color format to use. > > I don't like the "force" in the name. This just selects the color > format, let's just call it "color format" then. > In previous revisions, this was "preferred color format" and "actual color format", of which the latter has been dropped. I recommend reading the discussion for previous revisions. There are arguments for adding "actual color format" later and if it is added later, we'd end up with "color format" and "actual color format", which might be confusing, and it is why I chose to call it "force color format" because it clearly communicates intent and disambiguates it from "actual color format". [...] > > @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces = > > * drm_connector_attach_max_bpc_property() to create and attach the > > * property to the connector during initialization. > > * > > + * force color format: > > + * This property is used by userspace to change the used color format. > > When > > + * used the driver will use the selected format if valid for the > > hardware, > > All properties are always "used", they just can have different values. > You probably want to talk about the auto mode here. Maybe we can say something like: If userspace does not set the property or if it is explicitly set to zero, the driver will select the appropriate color format based on other constraints. > > > + * sink, and current resolution and refresh rate combination. Drivers to > > If valid? So when a value is not actually supported user space can still > set it? What happens then? How should user space figure out if the > driver and the sink support the format? The kernel does not expose this property unless it's implemented in the driver. This was originally "preferred color format". Perhaps the documentation should better reflect that it is now a mandatory constraint which fails the modeset if not satisfied. > > For the Colorspace prop, the kernel just exposes all formats it supports > (independent of the sink) and then makes it the job of user space to > figure out if the sink supports it. > > The same could be done here. Property value is exposed if the driver > supports it in general, commits can fail if the driver can't support it > for a specific commit because e.g. the resolution or refresh rate. User > space must look at the EDID/DisplayID/mode to figure out the supported > format for the sink. Yes, we can make it possible for userspace to discover which modes are supported by the monitor, but there are other constraints that need to be satisfied. This was discussed in the previous revision. In any case, these things can be added later and need not be a part of this change set. [...] Regards, Andri
[PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
From: Werner Sembach
Add a new general drm property "force color format" which can be used
by userspace to tell the graphics driver which color format to use.
Possible options are:
- auto (default/current behaviour)
- rgb
- ycbcr444
- ycbcr422 (supported by neither amdgpu or i915)
- ycbcr420
In theory the auto option should choose the best available option for the
current setup, but because of bad internal conversion some monitors look
better with rgb and some with ycbcr444.
Also, because of bad shielded connectors and/or cables, it might be
preferable to use the less bandwidth heavy ycbcr422 and ycbcr420 formats
for a signal that is less susceptible to interference.
In the future, automatic color calibration for screens might also depend on
this option being available.
Signed-off-by: Werner Sembach
Signed-off-by: Andri Yngvason
Tested-by: Andri Yngvason
---
Changes in v2:
- Renamed to "force color format" from "preferred color format"
- Removed Reported-by pointing to invalid email address
---
drivers/gpu/drm/drm_atomic_helper.c | 4 +++
drivers/gpu/drm/drm_atomic_uapi.c | 4 +++
drivers/gpu/drm/drm_connector.c | 48 +
include/drm/drm_connector.h | 16 ++
4 files changed, 72 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c
b/drivers/gpu/drm/drm_atomic_helper.c
index 39ef0a6addeba..1dabd164c4f09 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -707,6 +707,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
if (old_connector_state->max_requested_bpc !=
new_connector_state->max_requested_bpc)
new_crtc_state->connectors_changed = true;
+
+ if (old_connector_state->force_color_format !=
+ new_connector_state->force_color_format)
+ new_crtc_state->connectors_changed = true;
}
if (funcs->atomic_check)
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
b/drivers/gpu/drm/drm_atomic_uapi.c
index 29d4940188d49..e45949bf4615f 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -776,6 +776,8 @@ static int drm_atomic_connector_set_property(struct
drm_connector *connector,
state->max_requested_bpc = val;
} else if (property == connector->privacy_screen_sw_state_property) {
state->privacy_screen_sw_state = val;
+ } else if (property == connector->force_color_format_property) {
+ state->force_color_format = val;
} else if (connector->funcs->atomic_set_property) {
return connector->funcs->atomic_set_property(connector,
state, property, val);
@@ -859,6 +861,8 @@ drm_atomic_connector_get_property(struct drm_connector
*connector,
*val = state->max_requested_bpc;
} else if (property == connector->privacy_screen_sw_state_property) {
*val = state->privacy_screen_sw_state;
+ } else if (property == connector->force_color_format_property) {
+ *val = state->force_color_format;
} else if (connector->funcs->atomic_get_property) {
return connector->funcs->atomic_get_property(connector,
state, property, val);
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index b0516505f7ae9..e0535e58b4535 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1061,6 +1061,14 @@ static const struct drm_prop_enum_list
drm_dp_subconnector_enum_list[] = {
{ DRM_MODE_SUBCONNECTOR_Native, "Native"}, /* DP */
};
+static const struct drm_prop_enum_list drm_force_color_format_enum_list[] = {
+ { 0, "auto" },
+ { DRM_COLOR_FORMAT_RGB444, "rgb" },
+ { DRM_COLOR_FORMAT_YCBCR444, "ycbcr444" },
+ { DRM_COLOR_FORMAT_YCBCR422, "ycbcr422" },
+ { DRM_COLOR_FORMAT_YCBCR420, "ycbcr420" },
+};
+
DRM_ENUM_NAME_FN(drm_get_dp_subconnector_name,
drm_dp_subconnector_enum_list)
@@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces =
* drm_connector_attach_max_bpc_property() to create and attach the
* property to the connector during initialization.
*
+ * force color format:
+ * This property is used by userspace to change the used color format. When
+ * used the driver will use the selected format if valid for the hardware,
+ * sink, and current resolution and refresh rate combination. Drivers to
+ * use the function drm_connector_attach_force_color_format_property()
+ * to create and attach the property to the connector during
+ * initialization. Possible values are "auto", "rgb", "ycbcr444",
+ * "ycbcr422", and "ycbcr420".
+ *
* Connectors also have one standardized atomic property:
*
Re: [PATCH v2 2/4] drm/uAPI: Add "force color format" drm property as setting for userspace
On Mon, Jan 15, 2024 at 04:05:52PM +, Andri Yngvason wrote:
> From: Werner Sembach
>
> Add a new general drm property "force color format" which can be used
> by userspace to tell the graphics driver which color format to use.
I don't like the "force" in the name. This just selects the color
format, let's just call it "color format" then.
> Possible options are:
> - auto (default/current behaviour)
> - rgb
> - ycbcr444
> - ycbcr422 (supported by neither amdgpu or i915)
> - ycbcr420
>
> In theory the auto option should choose the best available option for the
> current setup, but because of bad internal conversion some monitors look
> better with rgb and some with ycbcr444.
>
> Also, because of bad shielded connectors and/or cables, it might be
> preferable to use the less bandwidth heavy ycbcr422 and ycbcr420 formats
> for a signal that is less susceptible to interference.
>
> In the future, automatic color calibration for screens might also depend on
> this option being available.
>
> Signed-off-by: Werner Sembach
> Signed-off-by: Andri Yngvason
> Tested-by: Andri Yngvason
> ---
>
> Changes in v2:
> - Renamed to "force color format" from "preferred color format"
> - Removed Reported-by pointing to invalid email address
>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 4 +++
> drivers/gpu/drm/drm_atomic_uapi.c | 4 +++
> drivers/gpu/drm/drm_connector.c | 48 +
> include/drm/drm_connector.h | 16 ++
> 4 files changed, 72 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c
> index 39ef0a6addeba..1dabd164c4f09 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -707,6 +707,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
> if (old_connector_state->max_requested_bpc !=
> new_connector_state->max_requested_bpc)
> new_crtc_state->connectors_changed = true;
> +
> + if (old_connector_state->force_color_format !=
> + new_connector_state->force_color_format)
> + new_crtc_state->connectors_changed = true;
> }
>
> if (funcs->atomic_check)
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c
> b/drivers/gpu/drm/drm_atomic_uapi.c
> index 29d4940188d49..e45949bf4615f 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -776,6 +776,8 @@ static int drm_atomic_connector_set_property(struct
> drm_connector *connector,
> state->max_requested_bpc = val;
> } else if (property == connector->privacy_screen_sw_state_property) {
> state->privacy_screen_sw_state = val;
> + } else if (property == connector->force_color_format_property) {
> + state->force_color_format = val;
> } else if (connector->funcs->atomic_set_property) {
> return connector->funcs->atomic_set_property(connector,
> state, property, val);
> @@ -859,6 +861,8 @@ drm_atomic_connector_get_property(struct drm_connector
> *connector,
> *val = state->max_requested_bpc;
> } else if (property == connector->privacy_screen_sw_state_property) {
> *val = state->privacy_screen_sw_state;
> + } else if (property == connector->force_color_format_property) {
> + *val = state->force_color_format;
> } else if (connector->funcs->atomic_get_property) {
> return connector->funcs->atomic_get_property(connector,
> state, property, val);
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index b0516505f7ae9..e0535e58b4535 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1061,6 +1061,14 @@ static const struct drm_prop_enum_list
> drm_dp_subconnector_enum_list[] = {
> { DRM_MODE_SUBCONNECTOR_Native, "Native"}, /* DP */
> };
>
> +static const struct drm_prop_enum_list drm_force_color_format_enum_list[] = {
> + { 0, "auto" },
> + { DRM_COLOR_FORMAT_RGB444, "rgb" },
> + { DRM_COLOR_FORMAT_YCBCR444, "ycbcr444" },
> + { DRM_COLOR_FORMAT_YCBCR422, "ycbcr422" },
> + { DRM_COLOR_FORMAT_YCBCR420, "ycbcr420" },
> +};
> +
> DRM_ENUM_NAME_FN(drm_get_dp_subconnector_name,
>drm_dp_subconnector_enum_list)
>
> @@ -1396,6 +1404,15 @@ static const u32 dp_colorspaces =
> * drm_connector_attach_max_bpc_property() to create and attach the
> * property to the connector during initialization.
> *
> + * force color format:
> + * This property is used by userspace to change the used color format. When
> + * used the driver will use the selected format if valid for the hardware,
All properties are always "used", they just can have different values.
