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

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Message-ID: <un2arvxos2kuyrqej4p4fs3jfd3kzpa4r5txoitoctfwl7hair@i2a5lu3p3iem>
Date: Wed, 24 Dec 2025 15:03:17 +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 11:10:35AM +0100, Marijn Suijten wrote:
> On 2025-11-21 14:02:08, 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
> 
> typo: executed.
> 
> > 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(-)
> > 
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index d1cfe81a3373..f468d054f5bd 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -774,24 +774,20 @@ static void _dpu_encoder_update_vsync_source(struct dpu_encoder_virt *dpu_enc,
> >  		return;
> >  	}
> >  
> > +	/* Set vsync source irrespective of mdp top support */
> 
> Unnecessary comment, it's clear from the code flow that vsync_cfg.vsync_source
> is passed down into both functions.
> 
> Perhaps we should pass disp_info->vsync_source directly into
> hw_intf->ops.vsync_sel() and only initialize vsync_cfg when hw_mdptop has the
> function, to make this clear.

No, because on DPU 8.0+ WD is also setup per intf.

> 
> > +	vsync_cfg.vsync_source = disp_info->vsync_source;
> > +
> >  	if (hw_mdptop->ops.setup_vsync_source) {
> >  		for (i = 0; i < dpu_enc->num_phys_encs; i++)
> >  			vsync_cfg.ppnumber[i] = dpu_enc->hw_pp[i]->idx;
> > +	}
> >  
> > -		vsync_cfg.pp_count = dpu_enc->num_phys_encs;
> 
> This change is not mentioned in the commit description.  While true that
> pp_count is only used by dpu_hw_setup_vsync_sel(), that is still a valid
> function to be called on DPU < 5; it denotes the amount of ppnumber[i] array
> entries are used above.
> 
> > -		vsync_cfg.frame_rate = drm_mode_vrefresh(&dpu_enc->base.crtc->state->adjusted_mode);
> 
> Same, also not mentioned in the commit description.  frame_rate
> is used by dpu_hw_setup_wd_timer() on DPU < 8.
> 
> > -
> > -		vsync_cfg.vsync_source = disp_info->vsync_source;
> > -
> > -		hw_mdptop->ops.setup_vsync_source(hw_mdptop, &vsync_cfg);
> 
> But all of the above comments don't matter if the call to setup_vsync_source()
> is removed entirely - it didn't move anywhere else.  This is not described in
> the commit message.

Fun, I missed it earlier. Thanks for pointing it out.

Teguh, since we need to fix watchdog on MDP 8.0+, I'll send v3 on my
own, if you don't mind.

> 
> - Marijn
> 
> > -
> > -		for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> > -			phys_enc = dpu_enc->phys_encs[i];
> > +	for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> > +		phys_enc = dpu_enc->phys_encs[i];
> >  
> > -			if (phys_enc->has_intf_te && phys_enc->hw_intf->ops.vsync_sel)
> > -				phys_enc->hw_intf->ops.vsync_sel(phys_enc->hw_intf,
> > -						vsync_cfg.vsync_source);
> > -		}
> > +		if (phys_enc->has_intf_te && phys_enc->hw_intf->ops.vsync_sel)
> > +			phys_enc->hw_intf->ops.vsync_sel(phys_enc->hw_intf,
> > +					vsync_cfg.vsync_source);
> >  	}
> >  }
> >  
> > -- 
> > 2.34.1
> > 

-- 
With best wishes
Dmitry