linux-kernel - Re: [PATCH v2 04/10] drm/amd/display: use eld_mutex to protect access to connector->eld

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Message-ID: <ab347745-80cc-4a5c-ab92-de6bc6bce3cc@amd.com>
Date: Mon, 16 Dec 2024 14:38:54 -0500
From: Harry Wentland <harry.wentland@....com>
To: Alex Deucher <alexdeucher@...il.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Leo Li <sunpeng.li@....com>, Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 Xinhui Pan <Xinhui.Pan@....com>, Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Phong LE <ple@...libre.com>, Inki Dae <inki.dae@...sung.com>,
 Seung-Woo Kim <sw0312.kim@...sung.com>,
 Kyungmin Park <kyungmin.park@...sung.com>,
 Krzysztof Kozlowski <krzk@...nel.org>, Alim Akhtar
 <alim.akhtar@...sung.com>, Jani Nikula <jani.nikula@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Tvrtko Ursulin <tursulin@...ulin.net>, Rob Clark <robdclark@...il.com>,
 Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 Alain Volmat <alain.volmat@...s.st.com>,
 Raphael Gallais-Pou <rgallaispou@...il.com>,
 Dave Stevenson <dave.stevenson@...pberrypi.com>,
 Maíra Canal <mcanal@...lia.com>,
 Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 amd-gfx@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-samsung-soc@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
 freedreno@...ts.freedesktop.org
Subject: Re: [PATCH v2 04/10] drm/amd/display: use eld_mutex to protect access
 to connector->eld



On 2024-12-16 10:31, Alex Deucher wrote:
> On Mon, Dec 16, 2024 at 10:12 AM Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
>>
>> On Mon, 16 Dec 2024 at 16:53, Harry Wentland <harry.wentland@....com> wrote:
>>>
>>>
>>>
>>> On 2024-12-10 16:20, Dmitry Baryshkov wrote:
>>>> On Fri, Dec 06, 2024 at 11:43:07AM +0200, Dmitry Baryshkov wrote:
>>>>> Reading access to connector->eld can happen at the same time the
>>>>> drm_edid_to_eld() updates the data. Take the newly added eld_mutex in
>>>>> order to protect connector->eld from concurrent access.
>>>>>
>>>>> Reviewed-by: Maxime Ripard <mripard@...nel.org>
>>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>>> ---
>>>>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 ++
>>>>>  1 file changed, 2 insertions(+)
>>>>
>>>> Harry, Leo, Rodrigo, Alex, Christian, Xinhui, any response to this one
>>>> and to the radeon patches? I'd like to be able to pick the series for
>>>> drm-misc and these two are not reviewed by you.
>>>>
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> index 19a58630e774029767bf2a27eb4ddf17e3c21129..04c68c320252b5ce9647f0606fb86fe57f347639 100644
>>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>>> @@ -1037,8 +1037,10 @@ static int amdgpu_dm_audio_component_get_eld(struct device *kdev, int port,
>>>>>                      continue;
>>>>>
>>>>>              *enabled = true;
>>>>> +            mutex_lock(&connector->eld_mutex);
>>>>>              ret = drm_eld_size(connector->eld);
>>>>>              memcpy(buf, connector->eld, min(max_bytes, ret));
>>>>> +            mutex_unlock(&connector->eld_mutex);
>>>
>>> All of this is wrapped by the adev->dm.audio_lock mutex. It might
>>> be safer to modify the audio_lock mutex so it only guards the
>>> aconnector->audio_inst access.
>>>
>>> But I don't see any way these mutexes would otherwise interact,
>>> so this change should be good as-is.
>>>
>>> Reviewed-by: Harry Wentland <harry.wentland@....com>
>>
>> Would you ack it to merge it through drm-misc? Or would you prefer to
>> pick up those two patches after merging drm-misc-next once the rest of
>> the series lands?
> 
> Merging through drm-misc is fine with me.
> 

Same.

Harry

> Thanks,
> 
> Alex
> 
>>
>>>
>>> Harry
>>>
>>>>>
>>>>>              break;
>>>>>      }
>>>>>
>>>>> --
>>>>> 2.39.5
>>>>>
>>>>
>>>
>>
>>
>> --
>> With best wishes
>> Dmitry