[alsa-devel] [PATCH v2 2/4] drm/i915: implement set_ncts callback

[libin.yang at intel.com]

From: Libin Yang <libin.yang at intel.com>

Display 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/i915_reg.h    |  2 +
 drivers/gpu/drm/i915/intel_audio.c | 95 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index ea46d68..da2d128 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7014,6 +7014,8 @@ enum skl_disp_power_wells {
 					_HSW_AUD_MISC_CTRL_A, \
 					_HSW_AUD_MISC_CTRL_B)
 
+#define HSW_AUD_PIPE_CONN_SEL_CTRL  0x650ac
+
 #define _HSW_AUD_DIP_ELD_CTRL_ST_A	0x650b4
 #define _HSW_AUD_DIP_ELD_CTRL_ST_B	0x651b4
 #define HSW_AUD_DIP_ELD_CTRL(pipe) _PIPE(pipe, \
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index dc32cf4..eddf37f 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -68,6 +68,30 @@ static const struct {
 	{ 148500, AUD_CONFIG_PIXEL_CLOCK_HDMI_148500 },
 };
 
+#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)
 {
@@ -514,12 +538,83 @@ static int i915_audio_component_get_cdclk_freq(struct device *dev)
 	return ret;
 }
 
+static int i915_audio_component_set_ncts(struct device *dev, int port,
+			int dev_entry, 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 i;
+	int n_low, n_up, n = 0;
+
+	/* 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) {
+				DRM_DEBUG_KMS("%s: crtc is NULL\n", __func__);
+				continue;
+			}
+			pipe = crtc->pipe;
+			break;
+		}
+	}
+
+	if (pipe == -1) {
+		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. Need set the N/CTS manually at some frequencies */
+	if ((mode->clock != TMDS_297M) &&
+		(mode->clock != TMDS_296M)) {
+		tmp = I915_READ(HSW_AUD_CFG(pipe));
+		tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
+		I915_WRITE(HSW_AUD_CFG(pipe), tmp);
+		return 0;
+	}
+
+	/* 3. calculate the N/CTS */
+	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;
+		}
+	}
+	if (n == 0)
+		return 0;
+	n_low = n & 0xfff;
+	n_up = (n >> 12) & 0xff;
+
+	/* 4. set the N/CTS */
+	tmp = I915_READ(HSW_AUD_CFG(pipe));
+	tmp |= AUD_CONFIG_N_PROG_ENABLE;
+	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);
+
+	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,
+	.set_ncts = i915_audio_component_set_ncts,
 };
 
 static int i915_audio_component_bind(struct device *i915_dev,
-- 
1.9.1