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

[Dmitry Baryshkov]

On 02/08/2023 15:07, Marek Vasut wrote:
> On 8/2/23 10:52, 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@xxxxxxx>
> > Cc: Robert Foss <rfoss@xxxxxxxxxx>
> > Cc: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Cc: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > Fixes: 8ddce13ae69 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA 
> > and EOT packet")
> > Reported-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
> > Link: 
> > https://lore.kernel.org/r/CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@xxxxxxxxxxxxxx/
> > Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
>
> This breaks LT9611 operation on i.MX8M Mini/Nano/Plus, so, NAK.
>
> I am currently using this LT9611 with Linux 6.1.y in production and this 
> is not acceptable. I also believe the correct fix is on the MSM side, 
> not on the LT9611 driver side, since MSM incorrectly implements these 
> flags.

Up to now we saw no proof that MSM incorrectly implements the flags.

--
With best wishes
Dmitry