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

[Jeykumar Sankaran <jsanka-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

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@chromium.org>
>> >
>> > 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@chromium.org>
>> > ---
>> >  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.

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
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