[alsa-devel] [PATCH v5 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 values, 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    |  8 ++++++++
 drivers/gpu/drm/i915/intel_audio.c | 40 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 6786e94..122b5bd 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7035,6 +7035,8 @@ 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, \
@@ -7049,6 +7051,12 @@ 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 96b97be..0dfdc77 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -140,6 +140,27 @@ static bool audio_rate_need_prog(struct intel_crtc *crtc,
 		return false;
 }
 
+static int audio_config_get_rate(struct drm_i915_private *dev_priv,
+						enum pipe pipe)
+{
+	uint32_t tmp;
+	int cvt_idx;
+	int base_rate, mul, div, rate;
+
+	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;
+	return rate;
+}
+
 static bool intel_eld_uptodate(struct drm_connector *connector,
 			       int reg_eldv, uint32_t bits_eldv,
 			       int reg_elda, uint32_t bits_elda,
@@ -261,6 +282,8 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
 	const uint8_t *eld = connector->eld;
 	uint32_t tmp;
 	int len, i;
+	int n_low, n_up, n;
+	int rate;
 
 	DRM_DEBUG_KMS("Enable audio codec on pipe %c, %u bytes ELD\n",
 		      pipe_name(pipe), drm_eld_size(eld));
@@ -296,12 +319,27 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
 	/* Enable timestamps */
 	tmp = I915_READ(HSW_AUD_CFG(pipe));
 	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
-	tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
 	tmp &= ~AUD_CONFIG_PIXEL_CLOCK_HDMI_MASK;
 	if (intel_pipe_has_type(intel_crtc, INTEL_OUTPUT_DISPLAYPORT))
 		tmp |= AUD_CONFIG_N_VALUE_INDEX;
 	else
 		tmp |= audio_config_hdmi_pixel_clock(mode);
+
+	tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
+	if (audio_rate_need_prog(intel_crtc, mode)) {
+		rate = audio_config_get_rate(dev_priv, pipe);
+		n = audio_config_get_n(mode, rate);
+		if (n != 0) {
+			n_low = n & 0xfff;
+			n_up = (n >> 12) & 0xff;
+			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);
 }
 
-- 
1.9.1