[alsa-devel] [PATCH] ALSA: hda - Reset sample sizes and max bitrates when reading ELD

[Anssi Hannula]

When a new HDMI/DP device is plugged in, hdmi_update_short_audio_desc()
is called for every SAD (Short Audio Descriptor) in the ELD data. For
LPCM coding type SAD defines the supported sample sizes. For several
other coding types (such as AC-3), a maximum bitrate is defined.

The maximum bitrate and sample size fields are not always cleared.
Therefore, if a device is unplugged and a different one is plugged in,
and the coding types of some SAD positions differ between the devices,
the old max_bitrate or sample_bits values will persist if the new SADs
do not define those values.

The leftover max_bitrate and sample_bits do not cause any issues other
than wrongly showing up in eld#X.Y procfs file and kernel log.

Fix that by always clearing sample_bits and max_bitrate when reading
SADs.

Signed-off-by: Anssi Hannula <anssi.hannula at iki.fi>
---
 sound/pci/hda/hda_eld.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/sound/pci/hda/hda_eld.c b/sound/pci/hda/hda_eld.c
index 009031f..4a66347 100644
--- a/sound/pci/hda/hda_eld.c
+++ b/sound/pci/hda/hda_eld.c
@@ -189,6 +189,9 @@ static void hdmi_update_short_audio_desc(struct cea_sad *a,
 	a->channels = GRAB_BITS(buf, 0, 0, 3);
 	a->channels++;
 
+	a->sample_bits = 0;
+	a->max_bitrate = 0;
+
 	a->format = GRAB_BITS(buf, 0, 3, 4);
 	switch (a->format) {
 	case AUDIO_CODING_TYPE_REF_STREAM_HEADER:
@@ -198,7 +201,6 @@ static void hdmi_update_short_audio_desc(struct cea_sad *a,
 
 	case AUDIO_CODING_TYPE_LPCM:
 		val = GRAB_BITS(buf, 2, 0, 3);
-		a->sample_bits = 0;
 		for (i = 0; i < 3; i++)
 			if (val & (1 << i))
 				a->sample_bits |= cea_sample_sizes[i + 1];
-- 
1.7.3