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

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

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.

Is there a W/A name for this?


BR,
Jani.


> ---
>  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);

-- 
Jani Nikula, Intel Open Source Technology Center
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