Re: [PATCH v2] drm/msm/dpu: Filter modes based on adjusted mode clock

[Xilin Wu]

On 5/7/2025 9:38 AM, Jessica Zhang wrote:
> Filter out modes that have a clock rate greater than the max core clock
> rate when adjusted for the perf clock factor
>
> This is especially important for chipsets such as QCS615 that have lower
> limits for the MDP max core clock.
>
> Since the core CRTC clock is at least the mode clock (adjusted for the
> perf clock factor) [1], the modes supported by the driver should be less
> than the max core clock rate.
>
> [1] https://elixir.bootlin.com/linux/v6.12.4/source/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c#L83
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Signed-off-by: Jessica Zhang <jessica.zhang@xxxxxxxxxxxxxxxx>
> ---

Hi. This patch effectively filters out the 3840x2160@120Hz mode on 
SC8280XP CRD. The calculated adjusted_mode_clk is 623700, which slightly 
exceeds the supported max core clock of 600000.

However, 4K 120Hz works flawlessly with the limit removed on this 
platform. I even tried connecting two 4K 120Hz displays, and they can 
work properly simultaneously. Is it possible to bring back support for 
this mode, or adjust the limits?


--
Best regards,
Xilin Wu <sophon@xxxxxxxxx>