Re: [PATCH] drm/msm: dpu: Don't reset dpu_enc->cur_master on .disable()

[Sean Paul <sean-p7yTbzM4H96eqtR555YLDQ@public.gmane.org>]

On Tue, Oct 02, 2018 at 11:09:47AM -0700, Jeykumar Sankaran wrote:
> On 2018-09-17 13:49, Sean Paul wrote:
> > From: Sean Paul <seanpaul@chromium.org>
> > 
> > cur_master in dpu_encoder is assigned at modeset and cleared on
> > .disable(). Unfortunately dpms (or enable/disable) does not guarantee a
> > modeset, so cur_master is NULL when we try to re-enable it.
> > 
> > This patch moves the NULL assignment to setup_display where it will be
> > re-assigned later in the function.
> > 
> The patch looks harmless to me. But the encoder->disable also calls
> .disable() on
> the physical encoders. If the DPMS is not invoking an enable, why does
> it need to access cur_master when all the physical encoders are in the
> disabled state?

DPMS is invoking enable, but cur_master is currently only set on modeset which
isn't invoked on DPMS.

Sean

> Can we clean up the usage of cur_master if possible in the dpms path?
> 
> Thanks,
> Jeykumar S.
> 
> 
> > Signed-off-by: Sean Paul <seanpaul@chromium.org>
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index c2e8985b4c54..ae03d8d43b27 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -1230,8 +1230,6 @@ static void dpu_encoder_virt_disable(struct
> > drm_encoder *drm_enc)
> >  			dpu_enc->phys_encs[i]->connector = NULL;
> >  	}
> > 
> > -	dpu_enc->cur_master = NULL;
> > -
> >  	DPU_DEBUG_ENC(dpu_enc, "encoder disabled\n");
> > 
> >  	dpu_rm_release(&dpu_kms->rm, drm_enc);
> > @@ -2072,6 +2070,8 @@ static int dpu_encoder_setup_display(struct
> > dpu_encoder_virt *dpu_enc,
> >  		return -EINVAL;
> >  	}
> > 
> > +	dpu_enc->cur_master = NULL;
> > +
> >  	memset(&phys_params, 0, sizeof(phys_params));
> >  	phys_params.dpu_kms = dpu_kms;
> >  	phys_params.parent = &dpu_enc->base;
> 
> -- 
> Jeykumar S

-- 
Sean Paul, Software Engineer, Google / Chromium OS
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