[Intel-gfx] [PATCH 2/4] drm/i915: Disable PSR2 while getting pipe CRC

[Dhinakaran Pandiyan]

On Wed, 2019-02-13 at 18:02 -0800, José Roberto de Souza wrote:
> As stated in CRC_CTL spec, after PSR entry state CRC will not be
> calculated anymore what is not a problem as IGT tests do some screen
> change and then request the pipe CRC right after the change so PSR
> will go to idle state and only will entry again after at least 6
> idles frames.
> 
> But for PSR2 it is more problematic as any change to the screen could
> trigger a selective/partial update causing the CRC value not to be
> calculated over the full frame.
Okay, that reasoning runs counter to my understanding. My understanding
is that the whole frame is fetched and processed at the pipe level but
the DDI sends selective blocks of pixels. So, if the CRC's are
calculated at the pipe level, the CRC should be for the full frame with
PSR2 having no effect? Checking bspec, I see there are DDI CRCs as
well, which should reflect the partial frame that PSR2 sends.

To get a better understanding, I'd like to know what the source for
mismatching CRCs is?


> So here it disables PSR2 and keep it disabled while user is
> requesting pipe CRC.
> 
> BSpec: 7536
> 
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h       |  1 +
>  drivers/gpu/drm/i915/intel_drv.h      |  1 +
>  drivers/gpu/drm/i915/intel_pipe_crc.c | 10 ++++++++++
>  drivers/gpu/drm/i915/intel_psr.c      | 23 +++++++++++++++++++++++
>  4 files changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h
> index 17fe942eaafa..609e9c5bd453 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -520,6 +520,7 @@ struct i915_psr {
>  	bool sink_not_reliable;
>  	bool irq_aux_error;
>  	u16 su_x_granularity;
> +	bool pipe_crc_enabled;
>  };
>  
>  enum intel_pch {
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 3398b28c053b..40ce7a600585 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -2103,6 +2103,7 @@ void intel_psr_short_pulse(struct intel_dp
> *intel_dp);
>  int intel_psr_wait_for_idle(const struct intel_crtc_state
> *new_crtc_state,
>  			    u32 *out_value);
>  bool intel_psr_enabled(struct intel_dp *intel_dp);
> +void intel_psr_crc_prepare_or_finish(struct drm_i915_private
> *dev_priv, enum pipe pipe, bool prepare);
>  
>  /* intel_quirks.c */
>  void intel_init_quirks(struct drm_i915_private *dev_priv);
> diff --git a/drivers/gpu/drm/i915/intel_pipe_crc.c
> b/drivers/gpu/drm/i915/intel_pipe_crc.c
> index a8554dc4f196..5d8772399f60 100644
> --- a/drivers/gpu/drm/i915/intel_pipe_crc.c
> +++ b/drivers/gpu/drm/i915/intel_pipe_crc.c
> @@ -583,6 +583,14 @@ int intel_crtc_verify_crc_source(struct drm_crtc
> *crtc, const char *source_name,
>  	return -EINVAL;
>  }
>  
> +static inline void intel_crtc_crc_prepare_or_finish(struct drm_crtc
> *crtc, bool prepare)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
> +	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> +
> +	intel_psr_crc_prepare_or_finish(dev_priv, intel_crtc->pipe,
> prepare);
> +}
> +
>  int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char
> *source_name)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
> @@ -609,6 +617,8 @@ int intel_crtc_set_crc_source(struct drm_crtc
> *crtc, const char *source_name)
>  	if (ret != 0)
>  		goto out;
>  
> +	intel_crtc_crc_prepare_or_finish(crtc, source !=
> INTEL_PIPE_CRC_SOURCE_NONE);
> +
>  	pipe_crc->source = source;
>  	I915_WRITE(PIPE_CRC_CTL(crtc->index), val);
>  	POSTING_READ(PIPE_CRC_CTL(crtc->index));
> diff --git a/drivers/gpu/drm/i915/intel_psr.c
> b/drivers/gpu/drm/i915/intel_psr.c
> index 08967836b48e..9c93138988aa 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -577,6 +577,9 @@ static bool intel_psr2_config_valid(struct
> intel_dp *intel_dp,
>  		return false;
>  	}
>  
> +	if (dev_priv->psr.pipe_crc_enabled)
> +		return false;
> +
>  	return true;
>  }
>  
> @@ -1291,3 +1294,23 @@ bool intel_psr_enabled(struct intel_dp
> *intel_dp)
>  
>  	return ret;
>  }
> +
> +void intel_psr_crc_prepare_or_finish(struct drm_i915_private
> *dev_priv, enum pipe pipe, bool prepare)
> +{
> +	bool fastset = false;
> +
> +	if (!CAN_PSR(dev_priv))
> +		return;
> +
> +	mutex_lock(&dev_priv->psr.lock);
> +
> +	if (dev_priv->psr.pipe == pipe) {
> +		dev_priv->psr.pipe_crc_enabled = prepare;
> +		fastset = !prepare || dev_priv->psr.psr2_enabled;
> +	}
> +
> +	mutex_unlock(&dev_priv->psr.lock);
> +
> +	if (fastset)
> +		intel_psr_fastset_force(dev_priv);
> +}