linux-kernel - Re: [PATCH] Revert "drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet"

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Message-ID: <CAA8EJppp_ZJr-DcoZGd1GZmWuo=AECNS+X9zx0dNB4Edn8M2zg@mail.gmail.com>
Date:   Wed, 2 Aug 2023 21:16:39 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Marek Vasut <marex@...x.de>
Cc:     Neil Armstrong <neil.armstrong@...aro.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Jagan Teki <jagan@...rulasolutions.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: Re: [PATCH] Revert "drm/bridge: lt9611: Do not generate HFP/HBP/HSA
 and EOT packet"

On Wed, 2 Aug 2023 at 20:34, Marek Vasut <marex@...x.de> wrote:
>
> On 8/2/23 15:38, Dmitry Baryshkov wrote:
> > On 02/08/2023 11:52, Neil Armstrong wrote:
> >> This reverts commit [1] to fix display regression on the Dragonboard 845c
> >> (SDM845) devboard.
> >>
> >> There's a mismatch on the real action of the following flags:
> >> - MIPI_DSI_MODE_VIDEO_NO_HSA
> >> - MIPI_DSI_MODE_VIDEO_NO_HFP
> >> - MIPI_DSI_MODE_VIDEO_NO_HBP
> >> which leads to a non-working display on qcom platforms.
> >>
> >> [1] 8ddce13ae696 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA and
> >> EOT packet")
> >>
> >> Cc: Marek Vasut <marex@...x.de>
> >> Cc: Robert Foss <rfoss@...nel.org>
> >> Cc: Jagan Teki <jagan@...rulasolutions.com>
> >> Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> >> Cc: Abhinav Kumar <quic_abhinavk@...cinc.com>
> >> Fixes: 8ddce13ae69 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA
> >> and EOT packet")
> >> Reported-by: Amit Pundir <amit.pundir@...aro.org>
> >> Link:
> >> https://lore.kernel.org/r/CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@mail.gmail.com/
> >> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> >> ---
> >>   drivers/gpu/drm/bridge/lontium-lt9611.c | 4 +---
> >>   1 file changed, 1 insertion(+), 3 deletions(-)
> >>
> > Acked-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org> #fix db845c
> >
> > The boards broken by [1] are used in production by different parties
> > since 5.10, breaking them doesn't seem more acceptable than breaking the
> > new out-of-tree iMX8m hardware.
>
> The MX8M is also in-tree, so this does not apply.

v6.5-rc4:

$ git grep lontium,lt9611 | grep -v 9611uxc
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:$id:
http://devicetree.org/schemas/display/bridge/lontium,lt9611.yaml#
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:
    - lontium,lt9611
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:
      compatible = "lontium,lt9611";
arch/arm64/boot/dts/qcom/sdm845-db845c.dts: compatible = "lontium,lt9611";
drivers/gpu/drm/bridge/lontium-lt9611.c: { "lontium,lt9611", 0 },
drivers/gpu/drm/bridge/lontium-lt9611.c: { .compatible = "lontium,lt9611" },

next-20230802:

$ git grep lontium,lt9611 | grep -v 9611uxc
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:$id:
http://devicetree.org/schemas/display/bridge/lontium,lt9611.yaml#
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:
    - lontium,lt9611
Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml:
      compatible = "lontium,lt9611";
arch/arm64/boot/dts/qcom/sdm845-db845c.dts: compatible = "lontium,lt9611";
drivers/gpu/drm/bridge/lontium-lt9611.c: { "lontium,lt9611", 0 },
drivers/gpu/drm/bridge/lontium-lt9611.c: { .compatible = "lontium,lt9611" },

Your device is not in the tree. Your commit broke existing users.

Can we please end the argument, land the fix (this revert) for 6.5 and
work on the solution for 6.6 or 6.7?

-- 
With best wishes
Dmitry