linux-kernel - Re: [PATCH v2] drm/msm/dpu: Set vsync source irrespective of mdp top support

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Message-ID: <oqiukznu3hkci3jslug4bwawkobqmcxl7v7dqrh5i6r3rirm7d@543kbgervkp6>
Date: Wed, 24 Dec 2025 14:43:46 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Marijn Suijten <marijn.suijten@...ainline.org>
Cc: Teguh Sobirin <teguh@...ir.in>, Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jesszhan0024@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        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: Set vsync source irrespective of mdp top
 support

On Wed, Dec 24, 2025 at 11:00:23AM +0100, Marijn Suijten wrote:
> On 2025-11-21 14:16:55, Dmitry Baryshkov wrote:
> > On Fri, Nov 21, 2025 at 02:02:08PM +0800, Teguh Sobirin wrote:
> > > Since DPU 5.x the vsync source TE setup is split between MDP TOP and
> > > INTF blocks.  Currently all code to setup vsync_source is only exectued
> > > if MDP TOP implements the setup_vsync_source() callback. However on
> > > DPU >= 8.x this callback is not implemented, making DPU driver skip all
> > > vsync setup. Move the INTF part out of this condition, letting DPU
> > > driver to setup TE vsync selection on all new DPU devices.
> > > 
> > > Signed-off-by: Teguh Sobirin <teguh@...ir.in>
> > > ---
> > > Changes in v2:
> > > - Corrected commit message suggested by Dmitry Baryshkov.
> > > - Link to v1: https://lore.kernel.org/linux-arm-msm/TYUPR06MB6099CBBE5090DB12A2C187E3DDFDA@TYUPR06MB6099.apcprd06.prod.outlook.com/
> > > ---
> > >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 22 +++++++++------------
> > >  1 file changed, 9 insertions(+), 13 deletions(-)
> > 
> > Fixes: e955a3f0d86e ("drm/msm/dpu: Implement tearcheck support on INTF block")
> 
> Back at that commit, setup_vsync_source was still always assigned:
> 
> https://github.com/torvalds/linux/blob/e955a3f0d86e4a789364af62495ac37546eb71c8/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_top.c#L260-L263
> 
> While that was technically a wrong assumption by me - I should've put this loop
> outside the hw_mdptop check in case that ever happened, it got unassigned in
> commit 2f69e5458447 ("drm/msm/dpu: skip watchdog timer programming through TOP
> on >= SM8450").

Fair enough,

Fixes: 2f69e5458447 ("drm/msm/dpu: skip watchdog timer programming through TOP on >= SM8450")

> 
> Note that this patch is a severe regression on DPU <5 and doesn't set up the WD
> timer on DPU [5, 8), but I'll comment in-line on the diff.
> 
> - Marijn

-- 
With best wishes
Dmitry