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

[Marek Vasut]

On 8/2/23 14:38, Dmitry Baryshkov wrote:
> 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 at denx.de>
>>> Cc: Robert Foss <rfoss at kernel.org>
>>> Cc: Jagan Teki <jagan at amarulasolutions.com>
>>> Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> Cc: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>> Fixes: 8ddce13ae69 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA 
>>> and EOT packet")
>>> Reported-by: Amit Pundir <amit.pundir at linaro.org>
>>> Link: 
>>> https://lore.kernel.org/r/CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@mail.gmail.com/
>>> Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
>>
>> 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.

Please read the whole "[PATCH 2/2] drm/bridge: lt9611: Do not generate 
HFP/HBP/HSA and EOT packet" discussion for context.