[Intel-gfx] [PATCH v2] drm/i915/display: program audio CDCLK-TS for keepalives

[Ville Syrjälä]

On Mon, Sep 13, 2021 at 07:40:04PM +0300, Kai Vehmanen wrote:
> XE_LPD display adds support for display audio codec keepalive feature.
> This feature works also when display codec is in D3 state and the audio
> link is off (BCLK off). To enable this functionality, display driver
> must update the AUD_TS_CDCLK_M/N registers whenever CDCLK is changed.
> Actual timestamps are generated only when the audio codec driver
> specifically enables the KeepAlive (KAE) feature.
> 
> This patch adds new hooks to intel_set_cdclk() in order to inform
> display audio driver when CDCLK change is started and when it is
> complete.
> 
> Bspec: 53679
> Signed-off-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_audio.c | 37 ++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_audio.h |  2 ++
>  drivers/gpu/drm/i915/display/intel_cdclk.c |  5 +++
>  drivers/gpu/drm/i915/i915_reg.h            |  4 +++
>  4 files changed, 48 insertions(+)
> 
> Changes V1->V2:
>  - addressed review comments Jani Nikula (Sep 10)
>  - added an initial call to intel_audio_cdclk_change_post() so 
>    that AUD_CDCLK initial configuration is always performance
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> index 532237588511..ff74dc4dc121 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -936,6 +936,40 @@ void intel_init_audio_hooks(struct drm_i915_private *dev_priv)
>  	}
>  }
>  
> +struct aud_ts_cdclk_m_n {
> +	u8 m;
> +	u16 n;
> +};
> +
> +void intel_audio_cdclk_change_pre(struct drm_i915_private *i915)
> +{
> +	if (DISPLAY_VER(i915) >= 13)
> +		intel_de_rmw(i915, AUD_TS_CDCLK_M, AUD_TS_CDCLK_M_EN, 0);
> +}
> +
> +static void get_aud_ts_cdclk_m_n(int refclk, int cdclk, struct aud_ts_cdclk_m_n *aud_ts)
> +{
> +	if (refclk == 24000)
> +		aud_ts->m = 12;

Wasn't there a single exception to this rule? Ie. should this be 
if (refclk == 24000 && cdclk != something) ?

> +	else
> +		aud_ts->m = 15;
> +
> +	aud_ts->n = cdclk * aud_ts->m / 24000;
> +}
> +
> +void intel_audio_cdclk_change_post(struct drm_i915_private *i915)
> +{
> +	struct aud_ts_cdclk_m_n aud_ts;
> +
> +	if (DISPLAY_VER(i915) >= 13) {
> +		get_aud_ts_cdclk_m_n(i915->cdclk.hw.ref, i915->cdclk.hw.cdclk, &aud_ts);
> +
> +		intel_de_write(i915, AUD_TS_CDCLK_N, aud_ts.n);
> +		intel_de_write(i915, AUD_TS_CDCLK_M, aud_ts.m | AUD_TS_CDCLK_M_EN);
> +		drm_dbg_kms(&i915->drm, "aud_ts_cdclk set to M=%u, N=%u\n", aud_ts.m, aud_ts.n);
> +	}
> +}
> +
>  static int glk_force_audio_cdclk_commit(struct intel_atomic_state *state,
>  					struct intel_crtc *crtc,
>  					bool enable)
> @@ -1318,6 +1352,9 @@ static void i915_audio_component_init(struct drm_i915_private *dev_priv)
>  		dev_priv->audio_freq_cntrl = aud_freq;
>  	}
>  
> +	/* init with current cdclk */
> +	intel_audio_cdclk_change_post(dev_priv);
> +
>  	dev_priv->audio_component_registered = true;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.h b/drivers/gpu/drm/i915/display/intel_audio.h
> index a3657c7a7ba2..dcb259dd2da7 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.h
> +++ b/drivers/gpu/drm/i915/display/intel_audio.h
> @@ -18,6 +18,8 @@ void intel_audio_codec_enable(struct intel_encoder *encoder,
>  void intel_audio_codec_disable(struct intel_encoder *encoder,
>  			       const struct intel_crtc_state *old_crtc_state,
>  			       const struct drm_connector_state *old_conn_state);
> +void intel_audio_cdclk_change_pre(struct drm_i915_private *dev_priv);
> +void intel_audio_cdclk_change_post(struct drm_i915_private *dev_priv);
>  void intel_audio_init(struct drm_i915_private *dev_priv);
>  void intel_audio_deinit(struct drm_i915_private *dev_priv);
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 9aec17b33819..a1365f31142d 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -24,6 +24,7 @@
>  #include <linux/time.h>
>  
>  #include "intel_atomic.h"
> +#include "intel_audio.h"
>  #include "intel_bw.h"
>  #include "intel_cdclk.h"
>  #include "intel_de.h"
> @@ -1943,6 +1944,8 @@ static void intel_set_cdclk(struct drm_i915_private *dev_priv,
>  		intel_psr_pause(intel_dp);
>  	}
>  
> +	intel_audio_cdclk_change_pre(dev_priv);
> +
>  	/*
>  	 * Lock aux/gmbus while we change cdclk in case those
>  	 * functions use cdclk. Not all platforms/ports do,
> @@ -1971,6 +1974,8 @@ static void intel_set_cdclk(struct drm_i915_private *dev_priv,
>  		intel_psr_resume(intel_dp);
>  	}
>  
> +	intel_audio_cdclk_change_post(dev_priv);
> +
>  	if (drm_WARN(&dev_priv->drm,
>  		     intel_cdclk_changed(&dev_priv->cdclk.hw, cdclk_config),
>  		     "cdclk state doesn't match!\n")) {
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index bd63760207b0..795775c9e2eb 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9734,6 +9734,10 @@ enum {
>  #define AUD_PIN_BUF_CTL		_MMIO(0x48414)
>  #define   AUD_PIN_BUF_ENABLE		REG_BIT(31)
>  
> +#define AUD_TS_CDCLK_M			_MMIO(0x65ea0)
> +#define   AUD_TS_CDCLK_M_EN		REG_BIT(31)
> +#define AUD_TS_CDCLK_N			_MMIO(0x65ea4)
> +
>  /* Display Audio Config Reg */
>  #define AUD_CONFIG_BE			_MMIO(0x65ef0)
>  #define HBLANK_EARLY_ENABLE_ICL(pipe)		(0x1 << (20 - (pipe)))
> -- 
> 2.32.0

-- 
Ville Syrjälä
Intel