[alsa-devel] [PATCH v3] drm: bridge/dw_hdmi: add audio sample channel status setting

[Cheng-Yi Chiang <cychiang@chromium.org>]

From: Yakir Yang <ykk@rock-chips.com>

When transmitting IEC60985 linear PCM audio, we configure the
Aduio Sample Channel Status information in the IEC60958 frame.
The status bit is already available in iec.status of hdmi_codec_params.

This fix the issue that audio does not come out on some monitors
(e.g. LG 22CV241)

Note that these registers are only for interfaces:
I2S audio interface, General Purpose Audio (GPA), or AHB audio DMA
(AHBAUDDMA).
For S/PDIF interface this information comes from the stream.

Currently this function dw_hdmi_set_channel_status is only called
from dw-hdmi-i2s-audio in I2S setup.

Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
---

Change from v2 to v3:
1. Reuse what is already set in iec.status in hw_param.
2. Remove all useless definition of registers and values.
3. Note that the original sampling frequency is not written to
   the channel status as we reuse create_iec958_consumer in pcm_iec958.c.
   Without that it can still play audio fine.

 .../drm/bridge/synopsys/dw-hdmi-i2s-audio.c   |  1 +
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c     | 20 +++++++++++++++++++
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.h     |  2 ++
 include/drm/bridge/dw_hdmi.h                  |  1 +
 4 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
index 34d8e837555f..20f4f92dd866 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
@@ -102,6 +102,7 @@ static int dw_hdmi_i2s_hw_params(struct device *dev, void *data,
 	}
 
 	dw_hdmi_set_sample_rate(hdmi, hparms->sample_rate);
+	dw_hdmi_set_channel_status(hdmi, hparms->iec.status);
 	dw_hdmi_set_channel_count(hdmi, hparms->channels);
 	dw_hdmi_set_channel_allocation(hdmi, hparms->cea.channel_allocation);
 
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index bd65d0479683..aa7efd4da1c8 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -582,6 +582,26 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
 	return n;
 }
 
+/*
+ * When transmitting IEC60958 linear PCM audio, these registers allow to
+ * configure the channel status information of all the channel status
+ * bits in the IEC60958 frame. For the moment this configuration is only
+ * used when the I2S audio interface, General Purpose Audio (GPA),
+ * or AHB audio DMA (AHBAUDDMA) interface is active
+ * (for S/PDIF interface this information comes from the stream).
+ */
+void dw_hdmi_set_channel_status(struct dw_hdmi *hdmi,
+				u8 *channel_status)
+{
+	/*
+	 * Set channel status register for frequency and word length.
+	 * Use default values for other registers.
+	 */
+	hdmi_writeb(hdmi, channel_status[3], HDMI_FC_AUDSCHNLS7);
+	hdmi_writeb(hdmi, channel_status[4], HDMI_FC_AUDSCHNLS8);
+}
+EXPORT_SYMBOL_GPL(dw_hdmi_set_channel_status);
+
 static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
 	unsigned long pixel_clk, unsigned int sample_rate)
 {
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
index 6988f12d89d9..fcff5059db24 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
@@ -158,6 +158,8 @@
 #define HDMI_FC_SPDDEVICEINF                    0x1062
 #define HDMI_FC_AUDSCONF                        0x1063
 #define HDMI_FC_AUDSSTAT                        0x1064
+#define HDMI_FC_AUDSCHNLS7                      0x106e
+#define HDMI_FC_AUDSCHNLS8                      0x106f
 #define HDMI_FC_DATACH0FILL                     0x1070
 #define HDMI_FC_DATACH1FILL                     0x1071
 #define HDMI_FC_DATACH2FILL                     0x1072
diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
index cf528c289857..4b3e863c4f8a 100644
--- a/include/drm/bridge/dw_hdmi.h
+++ b/include/drm/bridge/dw_hdmi.h
@@ -156,6 +156,7 @@ void dw_hdmi_setup_rx_sense(struct dw_hdmi *hdmi, bool hpd, bool rx_sense);
 
 void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate);
 void dw_hdmi_set_channel_count(struct dw_hdmi *hdmi, unsigned int cnt);
+void dw_hdmi_set_channel_status(struct dw_hdmi *hdmi, u8 *channel_status);
 void dw_hdmi_set_channel_allocation(struct dw_hdmi *hdmi, unsigned int ca);
 void dw_hdmi_audio_enable(struct dw_hdmi *hdmi);
 void dw_hdmi_audio_disable(struct dw_hdmi *hdmi);
-- 
2.23.0.162.g0b9fbb3734-goog

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