Re: [PATCH v2 1/2] drm/i915/dp: Enable DP audio stall fix for gen9 platforms

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

On Tue, 2016-10-25 at 11:47 +0300, Jani Nikula wrote:
> On Tue, 25 Oct 2016, Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> wrote:
> > Enabling DP audio stall fix is necessary to play audio over DP HBR2. So,
> > let's set this bit right before enabling the audio codec. Playing audio
> > without setting this bit results in pipe FIFO underruns.
> >
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> 
> The fix itself looks legit, but please move the enable to beginning of
> hsw_audio_codec_enable and disable to end of hsw_audio_codec_disable in
> intel_audio.c. Seems to me you don't have to have separate functions for
> this, just add it inline there.
> 

I thought of it, but I didn't find any instances reading/writing of
non-audio registers in intel_audio.c. So, left these functions outside.



> Is there a W/A name for this?
> 
> 
> BR,
> Jani.
> 
> 

Not yet.

-DK

> > ---
> >  drivers/gpu/drm/i915/i915_reg.h  |  5 +++++
> >  drivers/gpu/drm/i915/intel_ddi.c | 38 ++++++++++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_drv.h |  2 ++
> >  3 files changed, 45 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 00efaa1..76dac48 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -6236,6 +6236,11 @@ enum {
> >  #define SLICE_ECO_CHICKEN0			_MMIO(0x7308)
> >  #define   PIXEL_MASK_CAMMING_DISABLE		(1 << 14)
> >  
> > +#define _CHICKEN_TRANS_A	0x420C0
> > +#define _CHICKEN_TRANS_B	0x420C4
> > +#define CHICKEN_TRANS(tran) _MMIO_TRANS(tran, _CHICKEN_TRANS_A, _CHICKEN_TRANS_B)
> > +#define SPARE_13	(1<<13)
> > +
> >  /* WaCatErrorRejectionIssue */
> >  #define GEN7_SQ_CHICKEN_MBCUNIT_CONFIG		_MMIO(0x9030)
> >  #define  GEN7_SQ_CHICKEN_MBCUNIT_SQINTMOB	(1<<11)
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index fb18d69..84c91c1 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -1858,6 +1858,38 @@ void intel_ddi_fdi_post_disable(struct intel_encoder *intel_encoder,
> >  	I915_WRITE(FDI_RX_CTL(PIPE_A), val);
> >  }
> >  
> > +void gen9_enable_dp_audio_stall_fix(struct intel_crtc_state *pipe_config)
> > +{
> > +	struct drm_i915_private *dev_priv =
> > +		to_i915(pipe_config->base.crtc->dev);
> > +	enum transcoder cpu_transcoder = pipe_config->cpu_transcoder;
> > +	uint32_t temp;
> > +
> > +	if (intel_crtc_has_dp_encoder(pipe_config) &&
> > +	    pipe_config->port_clock >= 54000) {
> > +
> > +		temp = I915_READ(CHICKEN_TRANS(cpu_transcoder));
> > +		temp |= SPARE_13;
> > +		I915_WRITE(CHICKEN_TRANS(cpu_transcoder), temp);
> > +	}
> > +}
> > +
> > +void gen9_disable_dp_audio_stall_fix(struct intel_crtc_state *pipe_config)
> > +{
> > +	struct drm_i915_private *dev_priv =
> > +		to_i915(pipe_config->base.crtc->dev);
> > +	enum transcoder cpu_transcoder = pipe_config->cpu_transcoder;
> > +	uint32_t temp;
> > +
> > +	if (intel_crtc_has_dp_encoder(pipe_config) &&
> > +	    pipe_config->port_clock >= 54000) {
> > +
> > +		temp = I915_READ(CHICKEN_TRANS(cpu_transcoder));
> > +		temp &= ~SPARE_13;
> > +		I915_WRITE(CHICKEN_TRANS(cpu_transcoder), temp);
> > +	}
> > +}
> > +
> >  static void intel_enable_ddi(struct intel_encoder *intel_encoder,
> >  			     struct intel_crtc_state *pipe_config,
> >  			     struct drm_connector_state *conn_state)
> > @@ -1893,6 +1925,9 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder,
> >  	}
> >  
> >  	if (intel_crtc->config->has_audio) {
> > +		if (IS_GEN9(dev_priv))
> > +			gen9_enable_dp_audio_stall_fix(pipe_config);
> > +
> >  		intel_display_power_get(dev_priv, POWER_DOMAIN_AUDIO);
> >  		intel_audio_codec_enable(intel_encoder);
> >  	}
> > @@ -1912,6 +1947,9 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder,
> >  	if (intel_crtc->config->has_audio) {
> >  		intel_audio_codec_disable(intel_encoder);
> >  		intel_display_power_put(dev_priv, POWER_DOMAIN_AUDIO);
> > +
> > +		if (IS_GEN9(dev_priv))
> > +			gen9_disable_dp_audio_stall_fix(old_crtc_state);
> >  	}
> >  
> >  	if (type == INTEL_OUTPUT_EDP) {
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 4e90b07..ef02c62 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1189,6 +1189,8 @@ unsigned int intel_fb_align_height(struct drm_device *dev,
> >  				   uint64_t fb_format_modifier);
> >  u32 intel_fb_stride_alignment(const struct drm_i915_private *dev_priv,
> >  			      uint64_t fb_modifier, uint32_t pixel_format);
> > +void gen9_enable_dp_audio_stall_fix(struct intel_crtc_state *pipe_config);
> > +void gen9_disable_dp_audio_stall_fix(struct intel_crtc_state *pipe_config);
> >  
> >  /* intel_audio.c */
> >  void intel_init_audio_hooks(struct drm_i915_private *dev_priv);
> 

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