Re: [REGRESSION] Resolutions broken after "drm/msm: dsi: fix PLL init in bonded mode"

[Dmitry Baryshkov]

On Sun, Apr 26, 2026 at 03:38:49AM +0530, Mohit Dsor wrote:
> Hi Neil, all,
> 
> We are seeing a regression after:
> 
> drm/msm: dsi: fix PLL init in bonded mode
> https://lore.kernel.org/r/20251027-topic-sm8x50-fix-dsi-bonded-v1-1-a477cd3f907d@xxxxxxxxxx
> 
> Issue:
> - Resolutions are broken after this change. Like if we try to run 720p60 it will be 720p30.
>   Even though the byte_clk is set correctly, the bridge is receiving half the byte clock.
>   Some divider is getting set which is causing the byte_clk to get half, ultimately fps to
>   get half. Some other resolutions may or may not be broken

Please provide necessary excerpts from /sys/kernel/debug/clk/clk_summary
for the working and for the broken cases. Also if there is a difference
in DSI PHY registers, please capture those (see
/sys/kernel/debug/dri/*/kms, provide necessary DSI PHY regs).

> Reproduction:
> - Used QNX RB3Gen2 Core kit with lilliput display and lt9611uxc dsi to hdmi bridge.

What is lilliput? What is QNX RB3 Gen2? Is it the normal Thundercomm's
RB3 Gen2 or some other board sold with the same name?

> - Run 720p60 usecase on hdmi with dsi to hdmi bridge.
> 
> Expected behavior:
> - Display should support the expected resolutions correctly.
> 
> Actual behavior:
> - No display on lilliput display.
> 
> Additional details:
> - Reverting this change locally avoids the issue.
> 
> Could you please take a look?
> 
> Thanks,
> Mohit

-- 
With best wishes
Dmitry