ALSA: hda - HDMI sticky stream tag support

When we run the following commands in turn (with
CONFIG_SND_HDA_POWER_SAVE_DEFAULT=0),

	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: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 15 insertions, 6 deletions

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index ff8ad46cc50e..ec9c348336cc 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -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;
-        if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
+        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)
+                                break;
                 }
-        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;
 
         mutex_lock(&chip->open_mutex);
-        azx_dev = azx_assign_device(chip, substream->stream);
+        azx_dev = azx_assign_device(chip, substream);
         if (azx_dev == NULL) {
                 mutex_unlock(&chip->open_mutex);
                 return -EBUSY;