Commit ef18bede authored by Wu Fengguang's avatar Wu Fengguang Committed by Takashi Iwai
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ALSA: hda - HDMI sticky stream tag support

When we run the following commands in turn (with

	speaker-test -Dhw:0,3 -c2 -twav  # HDMI
	speaker-test -Dhw:0,0 -c2 -twav  # Analog

The second command will produce sound in the analog lineout _as well as_
HDMI sink. The root cause is, device 0 "reuses" the same stream tag that
was used by device 3, and the "intelhdmi - sticky stream id" patch leaves
the HDMI codec in a functional state. So the HDMI codec happily accepts
the audio samples which reuse its stream tag.

The proposed solution is to remember the last device each azx_dev was
assigned to, and prefer to
1) reuse the azx_dev (and hence the stream tag) the HDMI codec last used
2) or assign a never-used azx_dev for HDMI

With this patch and the above two speaker-test commands,
HDMI codec will use stream tag 8 and Analog codec will use 5.

The stream tag used by HDMI codec won't be reused by others, as long
as we don't run out of the 4 playback azx_dev's. The legacy Analog
codec will continue to use stream tag 5 because its device id is 0
(this is a bit tricky).
Signed-off-by: default avatarWu Fengguang <>
Signed-off-by: default avatarTakashi Iwai <>
parent 6b7b2849
......@@ -356,6 +356,7 @@ struct azx_dev {
unsigned char stream_tag; /* assigned stream */
unsigned char index; /* stream index */
int device; /* last device number assigned to */
unsigned int opened :1;
unsigned int running :1;
......@@ -1441,10 +1442,13 @@ static int __devinit azx_codec_configure(struct azx *chip)
/* assign a stream for the PCM */
static inline struct azx_dev *azx_assign_device(struct azx *chip, int stream)
static inline struct azx_dev *
azx_assign_device(struct azx *chip, struct snd_pcm_substream *substream)
int dev, i, nums;
struct azx_dev *res = NULL;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
dev = chip->playback_index_offset;
nums = chip->playback_streams;
} else {
......@@ -1453,10 +1457,15 @@ static inline struct azx_dev *azx_assign_device(struct azx *chip, int stream)
for (i = 0; i < nums; i++, dev++)
if (!chip->azx_dev[dev].opened) {
chip->azx_dev[dev].opened = 1;
return &chip->azx_dev[dev];
res = &chip->azx_dev[dev];
if (res->device == substream->pcm->device)
return NULL;
if (res) {
res->opened = 1;
res->device = substream->pcm->device;
return res;
/* release the assigned stream */
......@@ -1505,7 +1514,7 @@ static int azx_pcm_open(struct snd_pcm_substream *substream)
int err;
azx_dev = azx_assign_device(chip, substream->stream);
azx_dev = azx_assign_device(chip, substream);
if (azx_dev == NULL) {
return -EBUSY;
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