RE: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document adi,disable-lanes-override property
Hi All,
I would like to drop this patch as[1] and [2] fixes the issue
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpu/drm/bridge/adv7511/adv7533.c?h=next-20230406&id=9a0cdcd6649b76f0b7ceec0e55b0a718321e34d3
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpu/drm/bridge/adv7511/adv7533.c?h=next-20230406&id=ee0285e13455fdbce5de315bdbe91b5f198a2a06
Cheers,
Biju
> -Original Message-
> From: Biju Das
> Sent: Wednesday, March 9, 2022 3:11 PM
> To: David Airlie ; Daniel Vetter ; Rob
> Herring
> Cc: Biju Das ; Ricardo Cañuelo
> ; Laurent Pinchart
> ; dri-devel@lists.freedesktop.org;
> devicet...@vger.kernel.org; Geert Uytterhoeven ;
> Chris Paterson ; Biju Das
> ; Prabhakar Mahadev Lad lad...@bp.renesas.com>; linux-renesas-...@vger.kernel.org
> Subject: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document
> adi,disable-lanes-override property
>
> On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at lower
> frequencies causes display instability. On such platforms, it is better to
> avoid switching lanes from 4 to 3 as it needs different set of PLL parameter
> constraints to make the display stable with 3 lanes.
>
> This patch introduces 'adi,disable-lanes-override' property to disable lane
> switching at lower frequencies.
>
> Signed-off-by: Biju Das
> Reviewed-by: Lad Prabhakar
> ---
> .../devicetree/bindings/display/bridge/adi,adv7533.yaml | 5 +
> 1 file changed, 5 insertions(+)
>
> diff --git
> a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> index f36209137c8a..2dc378039d21 100644
> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> @@ -84,6 +84,11 @@ properties:
>timings for HDMI output.
> type: boolean
>
> + adi,disable-lanes-override:
> +description:
> + Disables the overriding lanes at lower frequencies.
> +type: boolean
> +
>adi,dsi-lanes:
> description: Number of DSI data lanes connected to the DSI host.
> $ref: /schemas/types.yaml#/definitions/uint32
> --
> 2.17.1
RE: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document adi,disable-lanes-override property
Hi Laurent,
Thanks for the feedback.
> Subject: Re: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document
> adi,disable-lanes-override property
>
> Hi Biju,
>
> Thank you for the patch.
>
> On Wed, Mar 09, 2022 at 03:11:08PM +, Biju Das wrote:
> > On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at
> > lower frequencies causes display instability. On such platforms, it is
> > better to avoid switching lanes from 4 to 3 as it needs different set
> > of PLL parameter constraints to make the display stable with 3 lanes.
>
> Is this because the PLL calculation code doesn't work properly, or because
> the hardware can't support this ?
PLL Calculation is correct, that is the reason it works for all resolution
with 4 lanes. There are 2 clocks generated by PLL5 which is connected to a mux
with clock sources, namely 'FOUTPOSTDIV' and 'FOUT1PH0'
This Mux is connected to DSI dividers.
'FOUTPOSTDIV' should be selected if (PLL_INPUT_FREQ/VCLK) is odd and 'FOUT1PH0'
should
be selected if it is even.
The PLL calculation makes use of even selection('FOUT1PH0') and video works for
all frequencies
with 4 lanes.
With 'FOUT1PH0' as clock source, if I switch to 3 lanes for lanes it doesn't
work.
But it work with 4lanes on all frequencies.
HW can support 3 lanes, if I set parameter to make (PLL_INPUT_FREQ/VCLK) odd
and select
'FOUTPOSTDIV' as clk source to DSI divider.
I am not sure about the rational behind the constraint to Switch to 3 lanes for
lower frequency for this ADV7535 chip, as on our platform it can work with
4lanes
on all frequencies.
Cheers,
Biju
>
> > This patch introduces 'adi,disable-lanes-override' property to disable
> > lane switching at lower frequencies.
> >
> > Signed-off-by: Biju Das
> > Reviewed-by: Lad Prabhakar
> > ---
> > .../devicetree/bindings/display/bridge/adi,adv7533.yaml | 5 +
> > 1 file changed, 5 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> > b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> > index f36209137c8a..2dc378039d21 100644
> > ---
> > a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> > +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yam
> > +++ l
> > @@ -84,6 +84,11 @@ properties:
> >timings for HDMI output.
> > type: boolean
> >
> > + adi,disable-lanes-override:
> > +description:
> > + Disables the overriding lanes at lower frequencies.
> > +type: boolean
> > +
> >adi,dsi-lanes:
> > description: Number of DSI data lanes connected to the DSI host.
> > $ref: /schemas/types.yaml#/definitions/uint32
>
> --
> Regards,
>
> Laurent Pinchart
Re: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document adi,disable-lanes-override property
Hi Biju,
Thank you for the patch.
On Wed, Mar 09, 2022 at 03:11:08PM +, Biju Das wrote:
> On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at
> lower frequencies causes display instability. On such platforms, it
> is better to avoid switching lanes from 4 to 3 as it needs different
> set of PLL parameter constraints to make the display stable with 3
> lanes.
Is this because the PLL calculation code doesn't work properly, or
because the hardware can't support this ?
> This patch introduces 'adi,disable-lanes-override' property to disable
> lane switching at lower frequencies.
>
> Signed-off-by: Biju Das
> Reviewed-by: Lad Prabhakar
> ---
> .../devicetree/bindings/display/bridge/adi,adv7533.yaml | 5 +
> 1 file changed, 5 insertions(+)
>
> diff --git
> a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> index f36209137c8a..2dc378039d21 100644
> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> @@ -84,6 +84,11 @@ properties:
>timings for HDMI output.
> type: boolean
>
> + adi,disable-lanes-override:
> +description:
> + Disables the overriding lanes at lower frequencies.
> +type: boolean
> +
>adi,dsi-lanes:
> description: Number of DSI data lanes connected to the DSI host.
> $ref: /schemas/types.yaml#/definitions/uint32
--
Regards,
Laurent Pinchart
Re: [PATCH 1/2] dt-bindings: drm: bridge: adi,adv7533: Document adi,disable-lanes-override property
On 09/03/2022 16:11, Biju Das wrote:
> On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at
> lower frequencies causes display instability. On such platforms, it
> is better to avoid switching lanes from 4 to 3 as it needs different
> set of PLL parameter constraints to make the display stable with 3
> lanes.
>
> This patch introduces 'adi,disable-lanes-override' property to disable
> lane switching at lower frequencies.
>
> Signed-off-by: Biju Das
> Reviewed-by: Lad Prabhakar
> ---
> .../devicetree/bindings/display/bridge/adi,adv7533.yaml | 5 +
> 1 file changed, 5 insertions(+)
>
> diff --git
> a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> index f36209137c8a..2dc378039d21 100644
> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
> @@ -84,6 +84,11 @@ properties:
>timings for HDMI output.
> type: boolean
>
> + adi,disable-lanes-override:
> +description:
> + Disables the overriding lanes at lower frequencies.
> +type: boolean
The bindings should not focus on desired feature/functionality of
driver, but hardware. You are now encoding the driver behavior in the
bindings.
Best regards,
Krzysztof
[PATCH 1/2] dt-bindings: drm: bridge: adi, adv7533: Document adi, disable-lanes-override property
On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at
lower frequencies causes display instability. On such platforms, it
is better to avoid switching lanes from 4 to 3 as it needs different
set of PLL parameter constraints to make the display stable with 3
lanes.
This patch introduces 'adi,disable-lanes-override' property to disable
lane switching at lower frequencies.
Signed-off-by: Biju Das
Reviewed-by: Lad Prabhakar
---
.../devicetree/bindings/display/bridge/adi,adv7533.yaml | 5 +
1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
index f36209137c8a..2dc378039d21 100644
--- a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml
@@ -84,6 +84,11 @@ properties:
timings for HDMI output.
type: boolean
+ adi,disable-lanes-override:
+description:
+ Disables the overriding lanes at lower frequencies.
+type: boolean
+
adi,dsi-lanes:
description: Number of DSI data lanes connected to the DSI host.
$ref: /schemas/types.yaml#/definitions/uint32
--
2.17.1
