[Intel-gfx] [PATCH v2 2/6] drm/i915/psr: Always wait for idle state when disabling PSR

[Dhinakaran Pandiyan]

On Fri, 2018-10-19 at 23:46 +0000, Souza, Jose wrote:
> On Fri, 2018-10-19 at 13:42 -0700, Dhinakaran Pandiyan wrote:
> > On Wednesday, October 10, 2018 5:41:20 PM PDT José Roberto de Souza
> > wrote:
> > > It should always wait for idle state when disabling PSR because 
"It" is ambiguous here. 

How about something along the lines of -
"Unconditionally wait for PSR hardware to idle when disabling PSR. Even
if a preceding front buffer invalidate already disabled the feature, a
wait for idle is required before for re-enabling". Feel free to ignore.


> > > PSR
> > > could be inactive due a call to intel_psr_exit() and while PSR is
> > > still being disabled asynchronously userspace could change the
> > > modeset causing a call to psr_disable() that will not wait for
> > > PSR
> > > idle and then PSR will be enabled again while PSR is still not
> > > idle.
> > > 
> > > v2: rebased on top of the patch reusing psr_exit()
> > > 
> > > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_psr.c | 41 ++++++++++++++------------
> > > ------
> > >  1 file changed, 18 insertions(+), 23 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > b/drivers/gpu/drm/i915/intel_psr.c index
> > > f698b3f45c6d..16d0e3df7de0
> > > 100644
> > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > @@ -661,8 +661,12 @@ static void intel_psr_exit(struct
> > > drm_i915_private
> > > *dev_priv) {
> > >  	u32 val;
> > > 
> > > -	if (!dev_priv->psr.active)
> > > +	if (!dev_priv->psr.active) {
> > > +		if (INTEL_GEN(dev_priv) >= 9)
> > > +			WARN_ON(I915_READ(EDP_PSR2_CTL) &
> > > EDP_PSR2_ENABLE);
> > > +		WARN_ON(I915_READ(EDP_PSR_CTL) & EDP_PSR_ENABLE);
> > 
> > Do we really need so many WARN_ONs needing MMIO reads? There are
> > almost as 
> > many lines of warnings as code in this function. I think at this
> > point, we 
> > know this code works and the warnings in psr_exit() should be
> > removed.
> 
> I'm just moving what intel_psr_disable_source() had but yes I think
> we
> can remove some WARN_ON() in intel_psr but I guess is better do in
> another patch.
> 
Please do so :)

Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > 
> > >  		return;
> > > +	}
> > > 
> > >  	if (dev_priv->psr.psr2_enabled) {
> > >  		val = I915_READ(EDP_PSR2_CTL);
> > > @@ -680,32 +684,23 @@ static void
> > >  intel_psr_disable_source(struct intel_dp *intel_dp)
> > >  {
> > >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > > +	i915_reg_t psr_status;
> > > +	u32 psr_status_mask;
> > > 
> > > -	if (dev_priv->psr.active) {
> > > -		i915_reg_t psr_status;
> > > -		u32 psr_status_mask;
> > > -
> > > -		intel_psr_exit(dev_priv);
> > > +	intel_psr_exit(dev_priv);
> > > 
> > > -		if (dev_priv->psr.psr2_enabled) {
> > > -			psr_status = EDP_PSR2_STATUS;
> > > -			psr_status_mask = EDP_PSR2_STATUS_STATE_MASK;
> > > -		} else {
> > > -			psr_status = EDP_PSR_STATUS;
> > > -			psr_status_mask = EDP_PSR_STATUS_STATE_MASK;
> > > -		}
> > > -
> > > -		/* Wait till PSR is idle */
> > > -		if (intel_wait_for_register(dev_priv,
> > > -					    psr_status,
> > > psr_status_mask, 0,
> > > -					    2000))
> > > -			DRM_ERROR("Timed out waiting for PSR Idle
> > > State\n");
> > > +	if (dev_priv->psr.psr2_enabled) {
> > > +		psr_status = EDP_PSR2_STATUS;
> > > +		psr_status_mask = EDP_PSR2_STATUS_STATE_MASK;
> > >  	} else {
> > > -		if (dev_priv->psr.psr2_enabled)
> > > -			WARN_ON(I915_READ(EDP_PSR2_CTL) &
> > > EDP_PSR2_ENABLE);
> > > -		else
> > > -			WARN_ON(I915_READ(EDP_PSR_CTL) &
> > > EDP_PSR_ENABLE);
> > > +		psr_status = EDP_PSR_STATUS;
> > > +		psr_status_mask = EDP_PSR_STATUS_STATE_MASK;
> > >  	}
> > > +
> > > +	/* Wait till PSR is idle */
> > > +	if (intel_wait_for_register(dev_priv, psr_status,
> > > psr_status_mask, 0,
> > > +				    2000))
> > > +		DRM_ERROR("Timed out waiting for PSR Idle State\n");
> > >  }
> > > 
> > >  static void intel_psr_disable_locked(struct intel_dp *intel_dp)
> > 
> > 
> > 
> 
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