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

[Marek Vasut]

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.