Re: [PATCH v3 4/7] drm/i915/psr: Begin to handle PSR/PSR2 errors set by sink

[Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>]

On Tue, 2018-06-05 at 22:45 +0000, Souza, Jose wrote:
> On Tue, 2018-05-22 at 16:58 -0700, Dhinakaran Pandiyan wrote:
> > 
> > On Thu, 2018-05-17 at 15:21 -0700, José Roberto de Souza wrote:
> > > 
> > > eDP spec states that sink device will do a short pulse in HPD
> > > line when there is a PSR/PSR2 error that needs to be handled by
> > > source, this is handling the first and most simples error:
> > > DP_PSR_SINK_INTERNAL_ERROR.
> > > 
> > > Here taking the safest approach and disabling PSR(at least until
> > > the next modeset), to avoid multiple rendering issues due to
> > > bad pannels.
> > > 
> > > v3:
> > > disabling PSR instead of exiting on error
> > > 
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_dp.c  |  2 ++
> > >  drivers/gpu/drm/i915/intel_drv.h |  1 +
> > >  drivers/gpu/drm/i915/intel_psr.c | 62 +++++++++++++++++++++++++-
> > > --
> > > --
> > > --
> > >  3 files changed, 52 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index b86da48fd38e..fa2851d4fb36 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -4479,6 +4479,8 @@ intel_dp_short_pulse(struct intel_dp
> > > *intel_dp)
> > >  	if (intel_dp_needs_link_retrain(intel_dp))
> > >  		return false;
> > >  
> > > +	intel_psr_short_pulse(intel_dp);
> > > +
> > >  	if (intel_dp->compliance.test_type ==
> > > DP_TEST_LINK_TRAINING)
> > > {
> > >  		DRM_DEBUG_KMS("Link Training Compliance Test
> > > requested\n");
> > >  		/* Send a Hotplug Uevent to userspace to start
> > > modeset */
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > > b/drivers/gpu/drm/i915/intel_drv.h
> > > index 4508be628450..892da65358e9 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -1921,6 +1921,7 @@ void intel_psr_compute_config(struct
> > > intel_dp
> > > *intel_dp,
> > >  			      struct intel_crtc_state
> > > *crtc_state);
> > >  void intel_psr_irq_control(struct drm_i915_private *dev_priv,
> > > bool
> > > debug);
> > >  void intel_psr_irq_handler(struct drm_i915_private *dev_priv,
> > > u32
> > > psr_iir);
> > > +void intel_psr_short_pulse(struct intel_dp *intel_dp);
> > >  
> > >  /* intel_runtime_pm.c */
> > >  int intel_power_domains_init(struct drm_i915_private *);
> > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > b/drivers/gpu/drm/i915/intel_psr.c
> > > index d88799482875..60797c8f9f0e 100644
> > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > @@ -741,6 +741,23 @@ static void hsw_psr_disable(struct intel_dp
> > > *intel_dp)
> > >  	psr_aux_io_power_put(intel_dp);
> > >  }
> > >  
> > > +static void psr_disable(struct intel_dp *intel_dp)
nit: How about __psr_disable()? Might be worth checking other files
what the right convention is.

> > > +{+	struct intel_digital_port *intel_dig_port =
> > > dp_to_dig_port(intel_dp);
> > > +	struct drm_device *dev = intel_dig_port->base.base.dev;
> > > +	struct drm_i915_private *dev_priv = to_i915(dev);
> > > +
> > > +	if (!dev_priv->psr.enabled)
> > > +		return;
> > > +
> > > +	dev_priv->psr.disable_source(intel_dp);
> > > +
> > > +	/* Disable PSR on Sink */
> > > +	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
> > > +	dev_priv->psr.enabled = NULL;
> > > +	cancel_delayed_work_sync(&dev_priv->psr.work);
> > > +}
> > > +
> > >  /**
> > >   * intel_psr_disable - Disable PSR
> > >   * @intel_dp: Intel DP
> > > @@ -762,20 +779,8 @@ void intel_psr_disable(struct intel_dp
> > > *intel_dp,
> > >  		return;
> > >  
> > >  	mutex_lock(&dev_priv->psr.lock);
> > > -	if (!dev_priv->psr.enabled) {
> > > -		mutex_unlock(&dev_priv->psr.lock);
> > > -		return;
> > > -	}
> > > -
> > > -	dev_priv->psr.disable_source(intel_dp);
> > > -
> > > -	/* Disable PSR on Sink */
> > > -	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
> > > -
> > > -	dev_priv->psr.enabled = NULL;
> > > +	psr_disable(intel_dp);
> > >  	mutex_unlock(&dev_priv->psr.lock);
> > > -
> > > -	cancel_delayed_work_sync(&dev_priv->psr.work);
> > >  }
> > >  
> > >  static bool psr_wait_for_idle(struct drm_i915_private *dev_priv)
> > > @@ -1014,3 +1019,34 @@ void intel_psr_init(struct
> > > drm_i915_private
> > > *dev_priv)
> > >  	dev_priv->psr.setup_vsc = hsw_psr_setup_vsc;
> > >  
> > >  }
> > > +
> > > +void intel_psr_short_pulse(struct intel_dp *intel_dp)
> > > +{
> > > +	struct intel_digital_port *intel_dig_port =
> > > dp_to_dig_port(intel_dp);
> > > +	struct drm_device *dev = intel_dig_port->base.base.dev;
> > > +	struct drm_i915_private *dev_priv = to_i915(dev);
> > > +	struct i915_psr *psr = &dev_priv->psr;
> > > +	uint8_t val;
> > > +
> > > +	if (!HAS_PSR(dev_priv) || !intel_dp_is_edp(intel_dp))
> > > +		return;
> > 	CAN_PSR(dev_priv) should take care of this.
> CAN_PSR is better and I will use that, but to remove the lock and 'if
> (psr->enabled != intel_dp)' we would also need to check
> i915_modparams.enable_psr. Even although we could end up doing the
> aux
> transactions bellow and PSR is disabled(because of one of the errors
> bellow), what do you think it is still worthy do it lockless?

That is a good point, avoiding DPCD read in case PSR is disabled is
indeed better.
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