[alsa-devel] [PATCH v4 2/4] drm/i915: implement sync_audio_rate callback

[libin.yang at intel.com]

From: Libin Yang <libin.yang at 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 at intel.com>
---
 drivers/gpu/drm/i915/intel_audio.c | 116 +++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index dc32cf4..9d6ba84 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 +564,78 @@ 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);
+		if (port == intel_dig_port->port) {
+			crtc = to_intel_crtc(intel_encoder->base.crtc);
+			if (!crtc ||
+				!intel_pipe_has_type(crtc, INTEL_OUTPUT_HDMI))
+				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