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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <e87a6ea4-dc88-485c-bee3-1d2e99081b6f@linaro.org>
Date: Mon, 20 Oct 2025 16:16:17 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Jessica Zhang <jessica.zhang@....qualcomm.com>,
 Rob Clark <robdclark@...il.com>, Dmitry Baryshkov <lumag@...nel.org>,
 Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Abhinav Kumar <quic_abhinavk@...cinc.com>, linux-arm-msm@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/msm/dpu: Filter modes based on adjusted mode clock

Hi,

On 10/20/25 16:15, Konrad Dybcio wrote:
> On 10/20/25 4:05 PM, neil.armstrong@...aro.org wrote:
>> Hi,
>>
>> On 5/7/25 03:38, 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@...aro.org>
>>> Signed-off-by: Jessica Zhang <jessica.zhang@....qualcomm.com>
>>
>> This change breaks the T14s OLED display, no modes are reported on the eDP connector.
>> msm_dpu ae01000.display-controller: [drm:update_display_info.part.0 [drm]] [CONNECTOR:41:eDP-1] Assigning EDID-1.4 digital sink color depth as 10 bpc.
>> msm_dpu ae01000.display-controller: [drm:update_display_info.part.0 [drm]] [CONNECTOR:41:eDP-1] ELD monitor
>> msm_dpu ae01000.display-controller: [drm:update_display_info.part.0 [drm]] [CONNECTOR:41:eDP-1] ELD size 20, SAD count 0
>> [drm:drm_mode_object_put.part.0 [drm]] OBJ ID: 113 (1)
>> msm_dpu ae01000.display-controller: [drm:drm_mode_prune_invalid [drm]] Rejected mode: "2880x1800": 120 652260 2880 2912 2920 2980 1800 1808 1816 1824 0x48 0x9 (CLOCK_HIGH)
>> msm_dpu ae01000.display-controller: [drm:drm_mode_prune_invalid [drm]] Rejected mode: "2880x1800": 60 652260 2880 2888 2920 2980 1800 1808 1816 3648 0x40 0x9 (CLOCK_HIGH)
>>
>> With this reverted on v6.18-rc, display works again.
> 
> https://lore.kernel.org/linux-arm-msm/20250923-modeclk-fix-v2-1-01fcd0b2465a@oss.qualcomm.com/

Thanks,
Neil

> 
> Konrad