Re: [PATCH 08/14] drm/i915: Disable FIFO underrun reporting around IBX transcoder B workaround

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 29 Oct 2015, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Doing the IBX transcoder B workaround causes underruns on
> pipe/transcoder A. Just hide them by disabling underrun reporting for
> pipe A around the workaround.
>
> It might be possible to avoid the underruns by moving the workaround
> to be applied only when enabling pipe A. But I was too lazy to try it
> right now, and the current method has been proven to work, so didn't
> want to change it too hastily.

Is it possible this enables underrun reporting on pipe A even if it
wasn't enabled before?

BR,
Jani.

>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c   | 11 +++++++++++
>  drivers/gpu/drm/i915/intel_drv.h  |  9 +++++++++
>  drivers/gpu/drm/i915/intel_hdmi.c | 11 +++++++++++
>  drivers/gpu/drm/i915/intel_sdvo.c | 11 +++++++++++
>  4 files changed, 42 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 8287df4..4a0fb63 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3957,6 +3957,13 @@ intel_dp_link_down(struct intel_dp *intel_dp)
>  	 * matching HDMI port to be enabled on transcoder A.
>  	 */
>  	if (HAS_PCH_IBX(dev) && crtc->pipe == PIPE_B && port != PORT_A) {
> +		/*
> +		 * We get CPU/PCH FIFO underruns on the other pipe when
> +		 * doing the workaround. Sweep them under the rug.
> +		 */
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +
>  		/* always enable with pattern 1 (as per spec) */
>  		DP &= ~(DP_PIPEB_SELECT | DP_LINK_TRAIN_MASK);
>  		DP |= DP_PORT_EN | DP_LINK_TRAIN_PAT_1;
> @@ -3966,6 +3973,10 @@ intel_dp_link_down(struct intel_dp *intel_dp)
>  		DP &= ~DP_PORT_EN;
>  		I915_WRITE(intel_dp->output_reg, DP);
>  		POSTING_READ(intel_dp->output_reg);
> +
> +		intel_wait_for_vblank_if_active(dev_priv->dev, PIPE_A);
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
>  	}
>  
>  	msleep(intel_dp->panel_power_down_delay);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 72cc272..35f1457 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1073,6 +1073,15 @@ intel_wait_for_vblank(struct drm_device *dev, int pipe)
>  {
>  	drm_wait_one_vblank(dev, pipe);
>  }
> +static inline void
> +intel_wait_for_vblank_if_active(struct drm_device *dev, int pipe)
> +{
> +	const struct intel_crtc *crtc =
> +		to_intel_crtc(intel_get_crtc_for_pipe(dev, pipe));
> +
> +	if (crtc->active)
> +		intel_wait_for_vblank(dev, pipe);
> +}
>  int ironlake_get_lanes_required(int target_clock, int link_bw, int bpp);
>  void vlv_wait_port_ready(struct drm_i915_private *dev_priv,
>  			 struct intel_digital_port *dport,
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 013bd7d..bccbe70 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1108,6 +1108,13 @@ static void intel_disable_hdmi(struct intel_encoder *encoder)
>  	 * matching DP port to be enabled on transcoder A.
>  	 */
>  	if (HAS_PCH_IBX(dev) && crtc->pipe == PIPE_B) {
> +		/*
> +		 * We get CPU/PCH FIFO underruns on the other pipe when
> +		 * doing the workaround. Sweep them under the rug.
> +		 */
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +
>  		temp &= ~SDVO_PIPE_B_SELECT;
>  		temp |= SDVO_ENABLE;
>  		/*
> @@ -1122,6 +1129,10 @@ static void intel_disable_hdmi(struct intel_encoder *encoder)
>  		temp &= ~SDVO_ENABLE;
>  		I915_WRITE(intel_hdmi->hdmi_reg, temp);
>  		POSTING_READ(intel_hdmi->hdmi_reg);
> +
> +		intel_wait_for_vblank_if_active(dev_priv->dev, PIPE_A);
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
>  	}
>  
>  	intel_hdmi->set_infoframes(&encoder->base, false, NULL);
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index c42b636..267e6cb 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -1464,12 +1464,23 @@ static void intel_disable_sdvo(struct intel_encoder *encoder)
>  	 * matching DP port to be enabled on transcoder A.
>  	 */
>  	if (HAS_PCH_IBX(dev_priv) && crtc->pipe == PIPE_B) {
> +		/*
> +		 * We get CPU/PCH FIFO underruns on the other pipe when
> +		 * doing the workaround. Sweep them under the rug.
> +		 */
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
> +
>  		temp &= ~SDVO_PIPE_B_SELECT;
>  		temp |= SDVO_ENABLE;
>  		intel_sdvo_write_sdvox(intel_sdvo, temp);
>  
>  		temp &= ~SDVO_ENABLE;
>  		intel_sdvo_write_sdvox(intel_sdvo, temp);
> +
> +		intel_wait_for_vblank_if_active(dev_priv->dev, PIPE_A);
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, PIPE_A, true);
> +		intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
>  	}
>  }

-- 
Jani Nikula, Intel Open Source Technology Center
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