HDMI Audio stops to work after setting some HDMI resolutions

Robotics & Edge Computing Jetson Systems Jetson TK1
1

Hi,
I’ve a problem with HDMI audio output. It seems that the HDMI audio is ok only with HDMI resolution >= 1920x1080. If I set a lower resolution, the HDMI audio stops to work and it doens’t work also if I return to a resolution >= 1920x1080. This happens on different types of HDMI screen, so I don’t think that it is a monitor problem.

Steps to reproduce:

  • start the system (automatically setted resolution is 1920x1080)

  • execute:
    /usr/bin/speaker-test --channels 2 --rate 48000 --device hw:0,3

    → audio is ok

  • execute:
    /usr/bin/xrandr --output HDMI-0 --mode 800x600
    /usr/bin/speaker-test --channels 2 --rate 48000 --device hw:0,3

    → audio is NOT ok, I can’t hear anything

  • execute:
    /usr/bin/xrandr --output HDMI-0 --mode 1920x1080
    /usr/bin/speaker-test --channels 2 --rate 48000 --device hw:0,3

    → audio is NOT ok, I can’t hear anything

  • reboot the system (automatically setted resolution is 1920x1080)

  • execute:
    /usr/bin/speaker-test --channels 2 --rate 48000 --device hw:0,3

    → audio is ok

Note that when I set the 800x600 resolution, I have those message in dmesg:
tegradc tegradc.1: hdmi: can’t set audio to 48000 at 49500000 pix_clock

Maybe I’ve to change some settings?

Thanks, best regards.

Ivan
2

IvanGolob,

Thanks for reporting. I’ll help check this.

3

Please check if this patch helps.

diff --git a/drivers/video/tegra/dc/hdmi.c b/drivers/video/tegra/dc/hdmi.c
index a732263..5edd950 100644
--- a/drivers/video/tegra/dc/hdmi.c
+++ b/drivers/video/tegra/dc/hdmi.c
@@ -4,7 +4,7 @@
  * Copyright (C) 2010 Google, Inc.
  * Author: Erik Gilling <konkers@android.com>
  *
- * Copyright (c) 2010-2015, NVIDIA CORPORATION, All rights reserved.
+ * Copyright (c) 2010-2016, NVIDIA CORPORATION, All rights reserved.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -445,6 +445,72 @@
 	return NULL;
 }
 
+struct tegra_hdmi_audio_config tegra_hdmi_audio_config_default[] = {
+	{148500000,	24576,	148500,	24000},
+	{0,		0,	0,	0},
+};
+
+static const struct tegra_hdmi_audio_config
+*tegra_hdmi_get_audio_config_default(unsigned audio_freq, unsigned pix_clock)
+{
+	struct tegra_hdmi_audio_config *table;
+	unsigned cts, N, fs, aval;
+
+	table = tegra_hdmi_audio_config_default;
+
+	/* N values are copied from spec for corresponding freq band */
+	switch (audio_freq) {
+	case AUDIO_FREQ_32K:
+		N = 4096;
+		fs = 32000;
+		aval = 24000;
+		break;
+	case AUDIO_FREQ_44_1K:
+		N = 6272;
+		fs = 44100;
+		aval = 20000;
+		break;
+	case AUDIO_FREQ_48K:
+		N = 6144;
+		fs = 48000;
+		aval = 24000;
+		break;
+	case AUDIO_FREQ_88_2K:
+		N = 12544;
+		fs = 88200;
+		aval = 20000;
+		break;
+	case AUDIO_FREQ_96K:
+		N = 12288;
+		fs = 96000;
+		aval = 24000;
+		break;
+	case AUDIO_FREQ_176_4K:
+		N = 25088;
+		fs = 176400;
+		aval = 20000;
+		break;
+	case AUDIO_FREQ_192K:
+		N = 24576;
+		fs = 192000;
+		aval = 24000;
+		break;
+	default:
+		/* we have non-matching freq band. Try to return default
+		   value instead of null table */
+		return table;
+	}
+
+	/* (Average CTS value) = (fTMDS_clock * N ) / (128 * fS) */
+	cts = ((pix_clock) / (128 * fs)) * N;
+
+	table->pix_clock = pix_clock;
+	table->cts = cts;
+	table->n = N;
+	table->aval = aval;
+
+	return table;
+}
 
 unsigned long tegra_hdmi_readl(struct tegra_dc_hdmi_data *hdmi,
 					     unsigned long reg)
@@ -1585,7 +1651,10 @@
 		dev_err(&dc->ndev->dev,
 			"hdmi: can't set audio to %d at %d pix_clock",
 			audio_freq, dc->mode.pclk);
-		return -EINVAL;
+		dev_err(&dc->ndev->dev,
+			"hdmi: falling back default configuration");
+		config = tegra_hdmi_get_audio_config_default(audio_freq,
+			dc->mode.pclk);
 	}
 
 	tegra_hdmi_writel(hdmi, 0, HDMI_NV_PDISP_HDMI_ACR_CTRL);
4

WayneWWW,

yes, the patch resolves the problem.

Thank you, best regards.

Ivan