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: <CADnq5_M8jC2w=XWB4BG+id60zfGFMMkSegmeg-y=VpSHC+FvFQ@mail.gmail.com>
Date: Mon, 16 Dec 2024 10:31:55 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Harry Wentland <harry.wentland@....com>, 
	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 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.

Thanks,

Alex

>
> >
> > Harry
> >
> > >>
> > >>              break;
> > >>      }
> > >>
> > >> --
> > >> 2.39.5
> > >>
> > >
> >
>
>
> --
> With best wishes
> Dmitry