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>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index ff8ad46..ec9c348 100644 (file)
--- 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;