[alsa-devel] [PATCH v4 4/4] drm/i915: set proper N/CTS in modeset

[Takashi Iwai]

On Mon, 10 Aug 2015 09:32:11 +0200,
libin.yang at intel.com wrote:
> 
> From: Libin Yang <libin.yang at intel.com>
> 
> When modeset occurs and the TMDS frequency is set to some
> speical value, the N/CTS need to be set manually if audio
> is playing.
> 
> Signed-off-by: Libin Yang <libin.yang at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h    |  6 ++++++
>  drivers/gpu/drm/i915/intel_audio.c | 42 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index da2d128..85f3beb 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7030,6 +7030,12 @@ enum skl_disp_power_wells {
>  					_HSW_AUD_DIG_CNVT_2)
>  #define DIP_PORT_SEL_MASK		0x3
>  
> +#define _HSW_AUD_STR_DESC_1		0x65084
> +#define _HSW_AUD_STR_DESC_2		0x65184
> +#define AUD_STR_DESC(pipe)	_PIPE(pipe, \
> +					 _HSW_AUD_STR_DESC_1,	\
> +					 _HSW_AUD_STR_DESC_2)
> +
>  #define _HSW_AUD_EDID_DATA_A		0x65050
>  #define _HSW_AUD_EDID_DATA_B		0x65150
>  #define HSW_AUD_EDID_DATA(pipe) _PIPE(pipe, \
> diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> index eddf37f..082f96d 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -235,6 +235,9 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
>  	const uint8_t *eld = connector->eld;
>  	uint32_t tmp;
>  	int len, i;
> +	int cvt_idx;
> +	int n_low, n_up, n;
> +	int base_rate, mul, div, rate;
>  
>  	DRM_DEBUG_KMS("Enable audio codec on pipe %c, %u bytes ELD\n",
>  		      pipe_name(pipe), drm_eld_size(eld));
> @@ -267,6 +270,21 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
>  	tmp |= AUDIO_ELD_VALID(pipe);
>  	I915_WRITE(HSW_AUD_PIN_ELD_CP_VLD, tmp);
>  
> +	if ((mode->clock == 297000) ||
> +		(mode->clock == DIV_ROUND_UP(297000 * 1000, 1001))) {

TMDS_297M and TMDS_296M can be used here?


> +		tmp = I915_READ(HSW_AUD_PIPE_CONN_SEL_CTRL);
> +		cvt_idx = (tmp >> pipe*8) & 0xff;
> +		tmp = I915_READ(AUD_STR_DESC(cvt_idx));
> +		base_rate = tmp & (1 << 14);
> +		if (base_rate == 0)
> +			rate = 48000;
> +		else
> +			rate = 44100;
> +		mul = (tmp & (0x7 << 11)) + 1;
> +		div = (tmp & (0x7 << 8)) + 1;
> +		rate = rate * mul / div;
> +	}
> +
>  	/* Enable timestamps */
>  	tmp = I915_READ(HSW_AUD_CFG(pipe));
>  	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> @@ -276,6 +294,30 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
>  		tmp |= AUD_CONFIG_N_VALUE_INDEX;
>  	else
>  		tmp |= audio_config_hdmi_pixel_clock(mode);
> +
> +	if ((mode->clock != 297000) &&
> +		(mode->clock != DIV_ROUND_UP(297000 * 1000, 1001))) {
> +		tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
> +	} else {
> +		for (i = 0; i < ARRAY_SIZE(aud_ncts); i++) {
> +			if ((rate == aud_ncts[i].sample_rate) &&
> +				(mode->clock == aud_ncts[i].clock)) {
> +				n = aud_ncts[i].n;
> +				break;
> +			}
> +		}

Missing initialization of n?

> +		if (n != 0) {
> +			tmp |= AUD_CONFIG_N_PROG_ENABLE;
> +			n_low = n & 0xfff;
> +			n_up = (n >> 12) & 0xff;
> +			tmp |= AUD_CONFIG_N_PROG_ENABLE;

You don't need to set it twice.

> +			tmp &= ~AUD_CONFIG_UPPER_N_MASK;
> +			tmp |= (n_up << AUD_CONFIG_UPPER_N_SHIFT);
> +			tmp &= ~AUD_CONFIG_LOWER_N_MASK;
> +			tmp |= (n_low << AUD_CONFIG_LOWER_N_SHIFT);
> +		}
> +	}
> +
>  	I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>  }
>  
> -- 
> 1.9.1
> 


thanks,

Takashi