ALSA: pcm: Introduce protocol version field to sw_params

For controlling the new fields more strictly, add sw_params.proto
field indicating the protocol version of the user-space.  User-space
should fill the SNDRV_PCM_VERSION value it's built with, then kernel
can know whether the new fields should be evaluated or not.

And now tstamp_type field is evaluated only when the valid value is
set there.  This avoids the wrong override of tstamp_type to zero,
which is SNDRV_PCM_TSTAMP_TYPE_GETTIMEOFDAY.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index a7e062f91f39..32168f7ffce3 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -391,8 +391,8 @@ struct snd_pcm_sw_params {
         snd_pcm_uframes_t silence_threshold;    /* min distance from noise for silence filling */
         snd_pcm_uframes_t silence_size;         /* silence block size */
         snd_pcm_uframes_t boundary;             /* pointers wrap point */
-        unsigned int tstamp_type;               /* timestamp type */
-        int pads;                               /* alignment, reserved */
+        unsigned int proto;                     /* protocol version */
+        unsigned int tstamp_type;               /* timestamp type (req. proto >= 2.0.12) */
         unsigned char reserved[56];             /* reserved for future */
 };