Re: [PATCH v2 15/24] drm/msm: dpu: Stop using encoder->crtc pointer

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On 2018-11-26 13:53, Sean Paul wrote:
On Mon, Nov 19, 2018 at 12:03:53PM -0800, Jeykumar Sankaran wrote:
On 2018-11-16 13:14, Sean Paul wrote:
> On Fri, Nov 16, 2018 at 12:05:09PM -0800, Jeykumar Sankaran wrote:
> > On 2018-11-16 10:42, Sean Paul wrote:
> > > From: Sean Paul <seanpaul@xxxxxxxxxxxx>
> > >
> > > It's for legacy drivers, for atomic drivers
crtc->state->encoder_mask
> > > should be used to map encoder to crtc.
> > >
> > > Changes in v2:
> > > - None
> > >
> > > Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> > > ---
> > >  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 46
> ++++++++----------------
> > >  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c  | 19 +++++++---
> > >  2 files changed, 29 insertions(+), 36 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > index 156f4c77ca44..a008a87a8113 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > @@ -284,9 +284,9 @@ enum dpu_intf_mode
dpu_crtc_get_intf_mode(struct
> > > drm_crtc *crtc)
> > >  		return INTF_MODE_NONE;
> > >  	}
> > >
> > > -	drm_for_each_encoder(encoder, crtc->dev)
> > > -		if (encoder->crtc == crtc)
> > > -			return dpu_encoder_get_intf_mode(encoder);
> > > +	/* TODO: Returns the first INTF_MODE, could there be
multiple
> > > values? */
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > crtc->state->encoder_mask)
> > > +		return dpu_encoder_get_intf_mode(encoder);
> > >
> > >  	return INTF_MODE_NONE;
> > >  }
> > > @@ -551,13 +551,9 @@ static void dpu_crtc_atomic_begin(struct
drm_crtc
> > > *crtc,
> > >  		spin_unlock_irqrestore(&dev->event_lock, flags);
> > >  	}
> > >
> > > -	list_for_each_entry(encoder,
&dev->mode_config.encoder_list, head)
> > > {
> > > -		if (encoder->crtc != crtc)
> > > -			continue;
> > > -
> > > -		/* encoder will trigger pending mask now */
> > > +	/* encoder will trigger pending mask now */
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > crtc->state->encoder_mask)
> > >  		dpu_encoder_trigger_kickoff_pending(encoder);
> > > -	}
> > >
> > >  	/*
> > >  	 * If no mixers have been allocated in
dpu_crtc_atomic_check(),
> > > @@ -704,7 +700,6 @@ static int
_dpu_crtc_wait_for_frame_done(struct
> > > drm_crtc *crtc)
> > >  void dpu_crtc_commit_kickoff(struct drm_crtc *crtc)
> > >  {
> > >  	struct drm_encoder *encoder;
> > > -	struct drm_device *dev = crtc->dev;
> > >  	struct dpu_crtc *dpu_crtc = to_dpu_crtc(crtc);
> > >  	struct dpu_kms *dpu_kms = _dpu_crtc_get_kms(crtc);
> > >  	struct dpu_crtc_state *cstate =
to_dpu_crtc_state(crtc->state);
> > > @@ -720,16 +715,13 @@ void dpu_crtc_commit_kickoff(struct drm_crtc
> > > *crtc)
> > >
> > >  	DPU_ATRACE_BEGIN("crtc_commit");
> > >
> > > -	list_for_each_entry(encoder,
&dev->mode_config.encoder_list, head)
> > > {
> > > +	/*
> > > +	 * Encoder will flush/start now, unless it has a tx
pending. If
> > > so, it
> > > +	 * may delay and flush at an irq event (e.g. ppdone)
> > > +	 */
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > +				  crtc->state->encoder_mask) {
> > >  		struct dpu_encoder_kickoff_params params = { 0 };
> > > -
> > > -		if (encoder->crtc != crtc)
> > > -			continue;
> > > -
> > > -		/*
> > > -		 * Encoder will flush/start now, unless it has a
tx
> > > pending.
> > > -		 * If so, it may delay and flush at an irq event
(e.g.
> > > ppdone)
> > > -		 */
> > >  		dpu_encoder_prepare_for_kickoff(encoder, &params);
> > >  	}
> > >
> > > @@ -754,12 +746,8 @@ void dpu_crtc_commit_kickoff(struct drm_crtc
> *crtc)
> > >
> > >  	dpu_vbif_clear_errors(dpu_kms);
> > >
> > > -	list_for_each_entry(encoder,
&dev->mode_config.encoder_list, head)
> > > {
> > > -		if (encoder->crtc != crtc)
> > > -			continue;
> > > -
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > crtc->state->encoder_mask)
> > >  		dpu_encoder_kickoff(encoder);
> > > -	}
> > We wont be holding the modeset locks here (and in crtc_atomic_begin)
> > in
> the
> > display thread. Is
> > it safe to iterate over encoder_mask?
>
> Hmm, I'm not sure I follow. AFAICT, there are 2 callsites for
> dpu_crtc_commit_kickoff():
>
> 1- dpu_kms_encoder_enable() which is called via the
> encoder->funcs->enable
> hook
> 2- dpu_kms_commit() which is called in the
> mode_config->funcs->atomic_commit_tail

atomic_commit_tail will be called from the WQ. Do we hold
the modeset locks in the WQ? I believe userspace thread will drop
the locks at the end of drm_mode_atomic_ioctl.

Accessing state is safe in non-blocking commits due to stalling any
subsequent
commits until the previous one has completed. Check out the comment at:

https://cgit.freedesktop.org/drm-tip/tree/drivers/gpu/drm/drm_atomic_helpe
r.c#n1754

Sean

Thanks for the link Sean!

Reviewed-by: Jeykumar Sankaran <jsanka@xxxxxxxxxxxxxx>


Thanks
>
> Both of these callsites will hold the modeset locks.
>
> Am I missing something?
>
> Thanks for your review,
>
> Sean
>
> > >
> > >  end:
> > >  	reinit_completion(&dpu_crtc->frame_done_comp);
> > > @@ -883,11 +871,8 @@ static void dpu_crtc_disable(struct drm_crtc
> *crtc)
> > >
> > >  	dpu_core_perf_crtc_update(crtc, 0, true);
> > >
> > > -	drm_for_each_encoder(encoder, crtc->dev) {
> > > -		if (encoder->crtc != crtc)
> > > -			continue;
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > crtc->state->encoder_mask)
> > >  		dpu_encoder_register_frame_event_callback(encoder,
NULL,
> > > NULL);
> > > -	}
> > >
> > >  	memset(cstate->mixers, 0, sizeof(cstate->mixers));
> > >  	cstate->num_mixers = 0;
> > > @@ -922,12 +907,9 @@ static void dpu_crtc_enable(struct drm_crtc
> *crtc,
> > >  	DRM_DEBUG_KMS("crtc%d\n", crtc->base.id);
> > >  	dpu_crtc = to_dpu_crtc(crtc);
> > >
> > > -	drm_for_each_encoder(encoder, crtc->dev) {
> > > -		if (encoder->crtc != crtc)
> > > -			continue;
> > > +	drm_for_each_encoder_mask(encoder, crtc->dev,
> > > crtc->state->encoder_mask)
> > >  		dpu_encoder_register_frame_event_callback(encoder,
> > >  				dpu_crtc_frame_event_cb, (void
*)crtc);
> > > -	}
> > >
> > >  	mutex_lock(&dpu_crtc->crtc_lock);
> > >  	trace_dpu_crtc_enable(DRMID(crtc), true, dpu_crtc);
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > index 1bec4540f3e1..64134d619748 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > @@ -320,7 +320,10 @@ static void dpu_kms_prepare_commit(struct
msm_kms
> > > *kms,
> > >  	struct dpu_kms *dpu_kms;
> > >  	struct msm_drm_private *priv;
> > >  	struct drm_device *dev;
> > > +	struct drm_crtc *crtc;
> > > +	struct drm_crtc_state *crtc_state;
> > >  	struct drm_encoder *encoder;
> > > +	int i;
> > >
> > >  	if (!kms)
> > >  		return;
> > > @@ -332,9 +335,13 @@ static void dpu_kms_prepare_commit(struct
msm_kms
> > > *kms,
> > >  	priv = dev->dev_private;
> > >  	pm_runtime_get_sync(&dpu_kms->pdev->dev);
> > >
> > > -	list_for_each_entry(encoder,
&dev->mode_config.encoder_list, head)
> > > -		if (encoder->crtc != NULL)
> > > +	/* Call prepare_commit for all affected encoders */
> > > +	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
> > > +		drm_for_each_encoder_mask(encoder, crtc->dev,
> > > +
crtc_state->encoder_mask) {
> > >  			dpu_encoder_prepare_commit(encoder);
> > > +		}
> > > +	}
> > >  }
> > >
> > >  /*
> > > @@ -344,13 +351,17 @@ static void dpu_kms_prepare_commit(struct
> msm_kms
> > > *kms,
> > >  void dpu_kms_encoder_enable(struct drm_encoder *encoder)
> > >  {
> > >  	const struct drm_encoder_helper_funcs *funcs =
> > > encoder->helper_private;
> > > -	struct drm_crtc *crtc = encoder->crtc;
> > > +	struct drm_device *dev = encoder->dev;
> > > +	struct drm_crtc *crtc;
> > >
> > >  	/* Forward this enable call to the commit hook */
> > >  	if (funcs && funcs->commit)
> > >  		funcs->commit(encoder);
> > >
> > > -	if (crtc && crtc->state->active) {
> > > +	drm_for_each_crtc(crtc, dev) {
> > > +		if (!(crtc->state->encoder_mask &
> > > drm_encoder_mask(encoder)))
> > > +			continue;
> > > +
> > >  		trace_dpu_kms_enc_enable(DRMID(crtc));
> > >  		dpu_crtc_commit_kickoff(crtc);
> > >  	}
> >
> > --
> > Jeykumar S

--
Jeykumar S

--
Jeykumar S



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