Re: [PATCH v3 2/4] drm/i915: implement sync_audio_rate callback

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

On Mon, 17 Aug 2015, "Yang, Libin" <libin.yang@intel.com> wrote:
> Hi Jani
>
>> -----Original Message-----
>> From: Jani Nikula [mailto:jani.nikula@linux.intel.com]
>> Sent: Monday, August 17, 2015 8:21 PM
>> To: Yang, Libin; alsa-devel@alsa-project.org; tiwai@suse.de; intel-
>> gfx@lists.freedesktop.org; daniel.vetter@ffwll.ch
>> Cc: Yang, Libin
>> Subject: Re: [PATCH v3 2/4] drm/i915: implement sync_audio_rate
>> callback
>> 
>> On Mon, 17 Aug 2015, libin.yang@intel.com wrote:
>> > From: Libin Yang <libin.yang@intel.com>
>> >
>> > HDMI audio may not work at some frequencies
>> > with the HW provided N/CTS.
>> >
>> > This patch sets the proper N value for the
>> > given audio sample rate at the impacted frequencies.
>> > At other frequencies, it will use the N/CTS value
>> > which HW provides.
>> >
>> > Signed-off-by: Libin Yang <libin.yang@intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/intel_audio.c | 117
>> +++++++++++++++++++++++++++++++++++++
>> >  1 file changed, 117 insertions(+)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_audio.c
>> b/drivers/gpu/drm/i915/intel_audio.c
>> > index dc32cf4..27add6a 100644
>> > --- a/drivers/gpu/drm/i915/intel_audio.c
>> > +++ b/drivers/gpu/drm/i915/intel_audio.c
>> > @@ -68,6 +68,31 @@ static const struct {
>> >  	{ 148500, AUD_CONFIG_PIXEL_CLOCK_HDMI_148500 },
>> >  };
>> >
>> > +/* HDMI N/CTS table */
>> > +#define TMDS_297M 297000
>> > +#define TMDS_296M DIV_ROUND_UP(297000 * 1000, 1001)
>> > +static const struct {
>> > +	int sample_rate;
>> > +	int clock;
>> > +	int n;
>> > +	int cts;
>> > +} aud_ncts[] = {
>> > +	{ 44100, TMDS_296M, 4459, 234375 },
>> > +	{ 44100, TMDS_297M, 4704, 247500 },
>> > +	{ 48000, TMDS_296M, 5824, 281250 },
>> > +	{ 48000, TMDS_297M, 5120, 247500 },
>> > +	{ 32000, TMDS_296M, 5824, 421875 },
>> > +	{ 32000, TMDS_297M, 3072, 222750 },
>> > +	{ 88200, TMDS_296M, 8918, 234375 },
>> > +	{ 88200, TMDS_297M, 9408, 247500 },
>> > +	{ 96000, TMDS_296M, 11648, 281250 },
>> > +	{ 96000, TMDS_297M, 10240, 247500 },
>> > +	{ 176400, TMDS_296M, 17836, 234375 },
>> > +	{ 176400, TMDS_297M, 18816, 247500 },
>> > +	{ 44100, TMDS_296M, 23296, 281250 },
>> > +	{ 44100, TMDS_297M, 20480, 247500 },
>> > +};
>> > +
>> >  /* get AUD_CONFIG_PIXEL_CLOCK_HDMI_* value for mode */
>> >  static u32 audio_config_hdmi_pixel_clock(struct drm_display_mode
>> *mode)
>> >  {
>> > @@ -90,6 +115,31 @@ static u32
>> audio_config_hdmi_pixel_clock(struct drm_display_mode *mode)
>> >  	return hdmi_audio_clock[i].config;
>> >  }
>> >
>> > +static int audio_config_get_n(struct drm_display_mode *mode, int
>> rate)
>> > +{
>> > +	int i;
>> > +
>> > +	for (i = 0; i < ARRAY_SIZE(aud_ncts); i++) {
>> > +		if ((rate == aud_ncts[i].sample_rate) &&
>> > +			(mode->clock == aud_ncts[i].clock)) {
>> > +			return aud_ncts[i].n;
>> > +		}
>> > +	}
>> > +	return 0;
>> > +}
>> > +
>> > +/* check whether N/CTS/M need be set manually */
>> > +static bool audio_rate_need_prog(struct intel_crtc *crtc,
>> > +					struct drm_display_mode
>> *mode)
>> > +{
>> > +	if (((mode->clock == TMDS_297M) ||
>> > +		 (mode->clock == TMDS_296M)) &&
>> > +		intel_pipe_has_type(crtc, INTEL_OUTPUT_HDMI))
>> > +		return true;
>> > +	else
>> > +		return false;
>> > +}
>> > +
>> >  static bool intel_eld_uptodate(struct drm_connector *connector,
>> >  			       int reg_eldv, uint32_t bits_eldv,
>> >  			       int reg_elda, uint32_t bits_elda,
>> > @@ -514,12 +564,79 @@ static int
>> i915_audio_component_get_cdclk_freq(struct device *dev)
>> >  	return ret;
>> >  }
>> >
>> > +static int i915_audio_component_sync_audio_rate(struct device
>> *dev,
>> > +						int port, int rate)
>> > +{
>> > +	struct drm_i915_private *dev_priv = dev_to_i915(dev);
>> > +	struct drm_device *drm_dev = dev_priv->dev;
>> > +	struct intel_encoder *intel_encoder;
>> > +	struct intel_digital_port *intel_dig_port;
>> > +	struct intel_crtc *crtc;
>> > +	struct drm_display_mode *mode;
>> > +	enum pipe pipe = -1;
>> > +	u32 tmp;
>> > +	int n_low, n_up, n;
>> > +
>> > +	/* 1. get the pipe */
>> > +	for_each_intel_encoder(drm_dev, intel_encoder) {
>> > +		intel_dig_port = enc_to_dig_port(&intel_encoder-
>> >base);
>> 
>> Mmmh, not all encoders are digital ports. enc_to_dig_port does a
>> container_of, so you can't just check for NULL either. IOW, you need
>> to
>> check the encoder->type (and you only care about HDMI here).
>
> Do you mean it should be:
> if (!crtc || !intel_pipe_has_type(crtc, INTEL_OUTPUT_HDMI))

No, just check for intel_encoder->type as the first thing in the loop,
and continue if it isn't HDMI.

	if (intel_encoder->type != INTEL_OUTPUT_HDMI)
        	continue;

>
> regards,
> Libin
>
>> 
>> > +		if (port == intel_dig_port->port) {
>> > +			crtc = to_intel_crtc(intel_encoder->base.crtc);
>> > +			if (!crtc) {
>> > +				DRM_DEBUG_KMS("%s: crtc is
>> NULL\n", __func__);
>> > +				continue;
>> > +			}
>> > +			pipe = crtc->pipe;
>> > +			break;
>> > +		}
>> > +	}
>> > +
>> > +	if (pipe == INVALID_PIPE) {
>> > +		DRM_DEBUG_KMS("no pipe for the port %c\n",
>> port_name(port));
>> > +		return -ENODEV;
>> > +	}
>> > +	DRM_DEBUG_KMS("pipe %c connects port %c\n",
>> > +				  pipe_name(pipe), port_name(port));
>> > +	mode = &crtc->config->base.adjusted_mode;
>> > +
>> > +	/* 2. check whether to set the N/CTS/M manually or not */
>> > +	if (!audio_rate_need_prog(crtc, mode)) {
>> > +		tmp = I915_READ(HSW_AUD_CFG(pipe));
>> > +		tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
>> > +		I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>> > +		return 0;
>> > +	}
>> > +
>> > +	n = audio_config_get_n(mode, rate);
>> > +	if (n == 0) {
>> > +		DRM_DEBUG_KMS("Using automatic mode for N value
>> on port %c\n",
>> > +					  port_name(port));
>> > +		tmp = I915_READ(HSW_AUD_CFG(pipe));
>> > +		tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
>> > +		I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>> > +		return 0;
>> > +	}
>> > +	n_low = n & 0xfff;
>> > +	n_up = (n >> 12) & 0xff;
>> > +
>> > +	/* 4. set the N/CTS/M */
>> > +	tmp = I915_READ(HSW_AUD_CFG(pipe));
>> > +	tmp &= ~(AUD_CONFIG_UPPER_N_MASK |
>> AUD_CONFIG_LOWER_N_MASK);
>> > +	tmp |= ((n_up << AUD_CONFIG_UPPER_N_SHIFT) |
>> > +			(n_low << AUD_CONFIG_LOWER_N_SHIFT) |
>> > +			AUD_CONFIG_N_PROG_ENABLE);
>> > +	I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>> > +
>> > +	return 0;
>> > +}
>> > +
>> >  static const struct i915_audio_component_ops
>> i915_audio_component_ops = {
>> >  	.owner		= THIS_MODULE,
>> >  	.get_power	= i915_audio_component_get_power,
>> >  	.put_power	= i915_audio_component_put_power,
>> >  	.codec_wake_override =
>> i915_audio_component_codec_wake_override,
>> >  	.get_cdclk_freq	= i915_audio_component_get_cdclk_freq,
>> > +	.sync_audio_rate = i915_audio_component_sync_audio_rate,
>> >  };
>> >
>> >  static int i915_audio_component_bind(struct device *i915_dev,
>> > --
>> > 1.9.1
>> >
>> 
>> --
>> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center
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