drm: bridge/dw_hdmi: add audio sample channel status setting

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>
Reviewed-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190911082646.134347-1-cychiang@chromium.org

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);
 

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)
 {

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

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);