Re: [PATCH 06/14] drm/i915: Check for FIFO underruns after modeset on IVB/HSW and CPT/PPT

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Oct 29, 2015 at 09:25:55PM +0200, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Due to the shared error interrupt on IVB/HSW and CPT/PPT we may not
> always get an interrupt on a FIFO underrun. But we can always do an
> explicit check (like we do on GMCH platforms that have no underrun
> interrupt).
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c       |   6 +-
>  drivers/gpu/drm/i915/intel_drv.h           |   3 +-
>  drivers/gpu/drm/i915/intel_fifo_underrun.c | 121 ++++++++++++++++++++++++-----
>  3 files changed, 105 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index c7cd9f7..e820147 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4719,9 +4719,9 @@ intel_post_enable_primary(struct drm_crtc *crtc)
>  	if (IS_GEN2(dev))
>  		intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, true);
>  
> -	/* Underruns don't raise interrupts, so check manually. */
> -	if (HAS_GMCH_DISPLAY(dev))
> -		i9xx_check_fifo_underruns(dev_priv);
> +	/* Underruns don't always raise interrupts, so check manually. */
> +	intel_check_cpu_fifo_underruns(dev_priv);
> +	intel_check_pch_fifo_underruns(dev_priv);
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 1a3bbdc..72cc272 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -959,7 +959,8 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>  					 enum pipe pipe);
>  void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>  					 enum transcoder pch_transcoder);
> -void i9xx_check_fifo_underruns(struct drm_i915_private *dev_priv);
> +void intel_check_cpu_fifo_underruns(struct drm_i915_private *dev_priv);
> +void intel_check_pch_fifo_underruns(struct drm_i915_private *dev_priv);
>  
>  /* i915_irq.c */
>  void gen5_enable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask);
> diff --git a/drivers/gpu/drm/i915/intel_fifo_underrun.c b/drivers/gpu/drm/i915/intel_fifo_underrun.c
> index 54daa66..a546fc3 100644
> --- a/drivers/gpu/drm/i915/intel_fifo_underrun.c
> +++ b/drivers/gpu/drm/i915/intel_fifo_underrun.c
> @@ -85,37 +85,28 @@ static bool cpt_can_enable_serr_int(struct drm_device *dev)
>  }
>  
>  /**
> - * i9xx_check_fifo_underruns - check for fifo underruns
> - * @dev_priv: i915 device instance
> + * intel_check_cpu_fifo_underruns - check for fifo underruns
> + * @crtc: pipe
>   *
>   * This function checks for fifo underruns on GMCH platforms. This needs to be
>   * done manually on modeset to make sure that we catch all underruns since they
>   * do not generate an interrupt by themselves on these platforms.
>   */

Stale kerneldoc above, just delete it. With that fixed:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> -void i9xx_check_fifo_underruns(struct drm_i915_private *dev_priv)
> +static void i9xx_check_fifo_underruns(struct intel_crtc *crtc)
>  {
> -	struct intel_crtc *crtc;
> -
> -	spin_lock_irq(&dev_priv->irq_lock);
> -
> -	for_each_intel_crtc(dev_priv->dev, crtc) {
> -		u32 reg = PIPESTAT(crtc->pipe);
> -		u32 pipestat;
> -
> -		if (crtc->cpu_fifo_underrun_disabled)
> -			continue;
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	u32 reg = PIPESTAT(crtc->pipe);
> +	u32 pipestat = I915_READ(reg) & 0xffff0000;
>  
> -		pipestat = I915_READ(reg) & 0xffff0000;
> -		if ((pipestat & PIPE_FIFO_UNDERRUN_STATUS) == 0)
> -			continue;
> +	assert_spin_locked(&dev_priv->irq_lock);
>  
> -		I915_WRITE(reg, pipestat | PIPE_FIFO_UNDERRUN_STATUS);
> -		POSTING_READ(reg);
> +	if ((pipestat & PIPE_FIFO_UNDERRUN_STATUS) == 0)
> +		return;
>  
> -		DRM_ERROR("pipe %c underrun\n", pipe_name(crtc->pipe));
> -	}
> +	I915_WRITE(reg, pipestat | PIPE_FIFO_UNDERRUN_STATUS);
> +	POSTING_READ(reg);
>  
> -	spin_unlock_irq(&dev_priv->irq_lock);
> +	DRM_ERROR("pipe %c underrun\n", pipe_name(crtc->pipe));
>  }
>  
>  static void i9xx_set_fifo_underrun_reporting(struct drm_device *dev,
> @@ -150,6 +141,23 @@ static void ironlake_set_fifo_underrun_reporting(struct drm_device *dev,
>  		ironlake_disable_display_irq(dev_priv, bit);
>  }
>  
> +static void ivybridge_check_fifo_underruns(struct intel_crtc *crtc)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	enum pipe pipe = crtc->pipe;
> +	uint32_t err_int = I915_READ(GEN7_ERR_INT);
> +
> +	assert_spin_locked(&dev_priv->irq_lock);
> +
> +	if ((err_int & ERR_INT_FIFO_UNDERRUN(pipe)) == 0)
> +		return;
> +
> +	I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));
> +	POSTING_READ(GEN7_ERR_INT);
> +
> +	DRM_ERROR("fifo underrun on pipe %c\n", pipe_name(pipe));
> +}
> +
>  static void ivybridge_set_fifo_underrun_reporting(struct drm_device *dev,
>  						  enum pipe pipe,
>  						  bool enable, bool old)
> @@ -202,6 +210,24 @@ static void ibx_set_fifo_underrun_reporting(struct drm_device *dev,
>  		ibx_disable_display_interrupt(dev_priv, bit);
>  }
>  
> +static void cpt_check_pch_fifo_underruns(struct intel_crtc *crtc)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	enum transcoder pch_transcoder = (enum transcoder) crtc->pipe;
> +	uint32_t serr_int = I915_READ(SERR_INT);
> +
> +	assert_spin_locked(&dev_priv->irq_lock);
> +
> +	if ((serr_int & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) == 0)
> +		return;
> +
> +	I915_WRITE(SERR_INT, SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));
> +	POSTING_READ(SERR_INT);
> +
> +	DRM_ERROR("pch fifo underrun on pch transcoder %c\n",
> +		  transcoder_name(pch_transcoder));
> +}
> +
>  static void cpt_set_fifo_underrun_reporting(struct drm_device *dev,
>  					    enum transcoder pch_transcoder,
>  					    bool enable, bool old)
> @@ -375,3 +401,56 @@ void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>  		DRM_ERROR("PCH transcoder %c FIFO underrun\n",
>  			  transcoder_name(pch_transcoder));
>  }
> +
> +/**
> + * intel_check_cpu_fifo_underruns - check for CPU fifo underruns immediately
> + * @dev_priv: i915 device instance
> + *
> + * Check for CPU fifo underruns immediately. Useful on IVB/HSW where the shared
> + * error interrupt may have been disabled, and so CPU fifo underruns won't
> + * necessarily raise an interrupt, and on GMCH platforms where underruns never
> + * raise an interrupt.
> + */
> +void intel_check_cpu_fifo_underruns(struct drm_i915_private *dev_priv)
> +{
> +	struct intel_crtc *crtc;
> +
> +	spin_lock_irq(&dev_priv->irq_lock);
> +
> +	for_each_intel_crtc(dev_priv->dev, crtc) {
> +		if (crtc->cpu_fifo_underrun_disabled)
> +			continue;
> +
> +		if (HAS_GMCH_DISPLAY(dev_priv))
> +			i9xx_check_fifo_underruns(crtc);
> +		else if (IS_GEN7(dev_priv))
> +			ivybridge_check_fifo_underruns(crtc);
> +	}
> +
> +	spin_unlock_irq(&dev_priv->irq_lock);
> +}
> +
> +/**
> + * intel_check_pch_fifo_underruns - check for PCH fifo underruns immediately
> + * @dev_priv: i915 device instance
> + *
> + * Check for PCH fifo underruns immediately. Useful on CPT/PPT where the shared
> + * error interrupt may have been disabled, and so PCH fifo underruns won't
> + * necessarily raise an interrupt.
> + */
> +void intel_check_pch_fifo_underruns(struct drm_i915_private *dev_priv)
> +{
> +	struct intel_crtc *crtc;
> +
> +	spin_lock_irq(&dev_priv->irq_lock);
> +
> +	for_each_intel_crtc(dev_priv->dev, crtc) {
> +		if (crtc->pch_fifo_underrun_disabled)
> +			continue;
> +
> +		if (HAS_PCH_CPT(dev_priv))
> +			cpt_check_pch_fifo_underruns(crtc);
> +	}
> +
> +	spin_unlock_irq(&dev_priv->irq_lock);
> +}
> -- 
> 2.4.10
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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