pcm: hw: Keep control data from kernel when SND_PCM_APPEND

Without this fix the application pointer would be reseted
whenever an application opens a device with SND_PCM_APPEND.

This would result in an Xrun if the device is already opened and
in running state and the appl_ptr is use.

Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c
index b93926c17b9913693b69d5fa70470ac5ae9d0916..65b198c573789de08fb4e5d7133a27e6ef832988 100644 (file)
--- a/src/pcm/pcm_hw.c
+++ b/src/pcm/pcm_hw.c
@@ -1004,16 +1004,28 @@ static int map_status_and_control_data(snd_pcm_t *pcm, bool force_fallback)
                hw->sync_ptr = NULL;
        }
 
-       /* Initialize the data. */
-       hw->mmap_control->appl_ptr = 0;
-       hw->mmap_control->avail_min = 1;
+       /* do not initialize in case of append and keep the values from the
+        * kernel
+        */
+       if (!(pcm->mode & SND_PCM_APPEND)) {
+               /* Initialize the data. */
+               hw->mmap_control->appl_ptr = 0;
+               hw->mmap_control->avail_min = 1;
+       }
        snd_pcm_set_hw_ptr(pcm, &hw->mmap_status->hw_ptr, hw->fd,
                           SNDRV_PCM_MMAP_OFFSET_STATUS +
                                offsetof(struct snd_pcm_mmap_status, hw_ptr));
        snd_pcm_set_appl_ptr(pcm, &hw->mmap_control->appl_ptr, hw->fd,
                             SNDRV_PCM_MMAP_OFFSET_CONTROL);
        if (hw->mmap_control_fallbacked) {
-               err = sync_ptr1(hw, 0);
+               unsigned int flags;
+               /* read appl_ptr and avail_min from kernel when device opened
+                * with SND_PCM_APPEND flag
+                */
+               if (pcm->mode & SND_PCM_APPEND)
+                       flags = SNDRV_PCM_SYNC_PTR_APPL |
+                               SNDRV_PCM_SYNC_PTR_AVAIL_MIN;
+               err = sync_ptr1(hw, flags);
                if (err < 0)
                        return err;
        }
@@ -1539,6 +1551,8 @@ int snd_pcm_hw_open_fd(snd_pcm_t **pcmp, const char *name, int fd,
                mode |= SND_PCM_NONBLOCK;
        if (fmode & O_ASYNC)
                mode |= SND_PCM_ASYNC;
+       if (fmode & O_APPEND)
+               mode |= SND_PCM_APPEND;
 
        if (ioctl(fd, SNDRV_PCM_IOCTL_PVERSION, &ver) < 0) {
                ret = -errno;