Re: [PATCH 09/22] drm/i915/audio: Read ELD buffer size from hardware

[Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>]

On Tue, 11 Oct 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> We currently read the ELD buffer size from hardware on g4x,
> but on ilk+ we just hardcode it to 84 bytes. Let's unify
> this and just do the hardware readout on all platforms,
> in case the size changes in the future or something.
>
> TODO: should perhaps do the readout during driver init and
> stash the results somewhere so that we could check that the
> connector's ELD actually fits and not even try to enable audio
> in that case...
>
> Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
> Cc: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>
> Cc: Takashi Iwai <tiwai@xxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>

> ---
>  drivers/gpu/drm/i915/display/intel_audio.c | 49 ++++++++++++++++++----
>  1 file changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> index 3f328913fc90..abca5f23673a 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -304,6 +304,15 @@ static int audio_config_hdmi_get_n(const struct intel_crtc_state *crtc_state,
>  	return 0;
>  }
>  
> +static int g4x_eld_buffer_size(struct drm_i915_private *i915)
> +{
> +	u32 tmp;
> +
> +	tmp = intel_de_read(i915, G4X_AUD_CNTL_ST);
> +
> +	return REG_FIELD_GET(G4X_ELD_BUFFER_SIZE_MASK, tmp);
> +}
> +
>  static void g4x_audio_codec_disable(struct intel_encoder *encoder,
>  				    const struct intel_crtc_state *old_crtc_state,
>  				    const struct drm_connector_state *old_conn_state)
> @@ -329,10 +338,11 @@ static void g4x_audio_codec_enable(struct intel_encoder *encoder,
>  
>  	tmp = intel_de_read(i915, G4X_AUD_CNTL_ST);
>  	tmp &= ~(G4X_ELD_VALID | G4X_ELD_ADDRESS_MASK);
> -	len = REG_FIELD_GET(G4X_ELD_BUFFER_SIZE_MASK, tmp);
>  	intel_de_write(i915, G4X_AUD_CNTL_ST, tmp);
>  
> +	len = g4x_eld_buffer_size(i915);
>  	len = min(drm_eld_size(eld) / 4, len);
> +
>  	for (i = 0; i < len; i++)
>  		intel_de_write(i915, G4X_HDMIW_HDMIEDID,
>  			       *((const u32 *)eld + i));
> @@ -442,6 +452,16 @@ hsw_audio_config_update(struct intel_encoder *encoder,
>  		hsw_hdmi_audio_config_update(encoder, crtc_state);
>  }
>  
> +static int hsw_eld_buffer_size(struct drm_i915_private *i915,
> +			       enum transcoder cpu_transcoder)
> +{
> +	u32 tmp;
> +
> +	tmp = intel_de_read(i915, HSW_AUD_DIP_ELD_CTRL(cpu_transcoder));
> +
> +	return REG_FIELD_GET(IBX_ELD_BUFFER_SIZE_MASK, tmp);
> +}
> +
>  static void hsw_audio_codec_disable(struct intel_encoder *encoder,
>  				    const struct intel_crtc_state *old_crtc_state,
>  				    const struct drm_connector_state *old_conn_state)
> @@ -615,9 +635,10 @@ static void hsw_audio_codec_enable(struct intel_encoder *encoder,
>  	tmp &= ~IBX_ELD_ADDRESS_MASK;
>  	intel_de_write(i915, HSW_AUD_DIP_ELD_CTRL(cpu_transcoder), tmp);
>  
> -	/* Up to 84 bytes of hw ELD buffer */
> -	len = min(drm_eld_size(eld), 84);
> -	for (i = 0; i < len / 4; i++)
> +	len = hsw_eld_buffer_size(i915, cpu_transcoder);
> +	len = min(drm_eld_size(eld) / 4, len);
> +
> +	for (i = 0; i < len; i++)
>  		intel_de_write(i915, HSW_AUD_EDID_DATA(cpu_transcoder),
>  			       *((const u32 *)eld + i));
>  
> @@ -658,6 +679,19 @@ static void ilk_audio_regs_init(struct drm_i915_private *i915,
>  	}
>  }
>  
> +static int ilk_eld_buffer_size(struct drm_i915_private *i915,
> +			       enum pipe pipe)
> +{
> +	struct ilk_audio_regs regs;
> +	u32 tmp;
> +
> +	ilk_audio_regs_init(i915, pipe, &regs);
> +
> +	tmp = intel_de_read(i915, regs.aud_cntl_st);
> +
> +	return REG_FIELD_GET(IBX_ELD_BUFFER_SIZE_MASK, tmp);
> +}
> +
>  static void ilk_audio_codec_disable(struct intel_encoder *encoder,
>  				    const struct intel_crtc_state *old_crtc_state,
>  				    const struct drm_connector_state *old_conn_state)
> @@ -732,9 +766,10 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
>  	tmp &= ~IBX_ELD_ADDRESS_MASK;
>  	intel_de_write(i915, regs.aud_cntl_st, tmp);
>  
> -	/* Up to 84 bytes of hw ELD buffer */
> -	len = min(drm_eld_size(eld), 84);
> -	for (i = 0; i < len / 4; i++)
> +	len = ilk_eld_buffer_size(i915, pipe);
> +	len = min(drm_eld_size(eld) / 4, len);
> +
> +	for (i = 0; i < len; i++)
>  		intel_de_write(i915, regs.hdmiw_hdmiedid,
>  			       *((const u32 *)eld + i));

-- 
Jani Nikula, Intel Open Source Graphics Center