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Subject[PATCH v3] drm: bridge/dw_hdmi: add audio sample channel status setting
From: Yakir Yang <>

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
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 <>
Signed-off-by: Cheng-Yi Chiang <>

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);
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_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);
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