linux-kernel - Re: [PATCH RFC RFT] drm/msm: adreno: attach the GMU device to a driver

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 for Android: free password hash cracker in your pocket

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

Message-ID: <a15e8316-96cb-452d-b2b8-731eeb6d25d3@oss.qualcomm.com>
Date: Thu, 30 Oct 2025 10:52:53 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
        Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC RFT] drm/msm: adreno: attach the GMU device to a
 driver

On 10/24/25 11:11 AM, Neil Armstrong wrote:
> On 10/24/25 10:55, Konrad Dybcio wrote:
>> On 10/23/25 10:27 AM, Neil Armstrong wrote:
>>> On 10/22/25 19:09, Konrad Dybcio wrote:
>>>> On 10/22/25 2:44 PM, Neil Armstrong wrote:
>>>>> Due to the sync_state is enabled by default in pmdomain & CCF since v6.17,
>>>>> the GCC and GPUCC sync_state would stay pending, leaving the resources in
>>>>> full performance:
>>>>> gcc-x1e80100 100000.clock-controller: sync_state() pending due to 3d6a000.gmu
>>>>> gpucc-x1e80100 3d90000.clock-controller: sync_state() pending due to 3d6a000.gmu
>>>>
>>>> Does this *actually* cause any harm, by the way?
>>>
>>> ?
>>>
>>>>
>>>> For example on x1e, GMU refers to 2 GPU_CC GDSCs, GPU_CC refers
>>>> to a pair of GCC clocks and GCC refers to VDD_CX
>>>>
>>>> and I see these prints, yet:
>>>>
>>>> /sys/kernel/debug/pm_genpd/gpu_cx_gdsc/current_state:off-0
>>>> /sys/kernel/debug/pm_genpd/gpu_gx_gdsc/current_state:off-0
>>>>
>>>> /sys/kernel/debug/pm_genpd/cx/current_state:on
>>>> /sys/kernel/debug/pm_genpd/cx/perf_state:256 # because of USB3 votes
>>>>
>>>> I'm not super sure where that sync_state comes from either (maybe
>>>> dev_set_drv_sync_state in pmdomain/core?)
>>>
>>> The way we handle the GMU so far is wrong, it abuses the driver model.
>>>
>>> And this is a symptom, whatever the impact it has, it needs to be fixed
>>> in a proper way.
>>>
>>> The sync_state is retained because the gmu device is never probed but
>>> has some clocks and power domains attached to it, which is clearly wrong.
>>
>> Yes I agree, however I'm only debating the commit message claims of
>> 'leaving the resources in full performance', which doesn't seem to be
>> true
> 
> OK so the wording may be a little bit extreme, perhaps something like:
> the GCC and GPUCC sync_state would stay pending, leaving the unused
> power domains enabled for the lifetime of the system.

The debugfs reads above suggest this is actually not happening

Konrad