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

[libin.yang at intel.com]

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 0b1cd72..94f7f8b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7026,6 +7026,12 @@ 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 f1148cd..df514b7 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -233,6 +233,9 @@ 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));
@@ -265,6 +268,21 @@ 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))) {
+		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;
@@ -274,6 +292,30 @@ 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;
+			}
+		}
+		if (n != 0) {
+			tmp |= AUD_CONFIG_N_PROG_ENABLE;
+			n_low = n & 0xfff;
+			n_up = (n >> 12) & 0xff;
+			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);
 }
 
-- 
1.9.1