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pcm: hw: add a helper function to request hwsync without side-effects

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SNDRV_PCM_IOCTL_SYNC_PTR command for ioctl(2) with
SNDRV_PCM_SYNC_PTR_HWSYNC flag has an effect to update hw_ptr.
This is an alternative of SNDRV_PCM_IOCTL_HWSYNC but caller can get
current status simultaneously.

This commit adds a helper function just to issue hwsync. To avoid
side-effect to change appl_ptr and avail_min, this commit uses
SNDRV_PCM_SYNC_PTR_APPL and SNDRV_PCM_SYNC_PTR_AVAIL_MIN flags.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2017-06-30 20:37:26 +09:00 • committed by Takashi Iwai
parent 78f3165a9e
commit 8a3df40bce
1 changed files with 17 additions and 2 deletions
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19
src/pcm/pcm_hw.c
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@ -151,6 +151,21 @@ static int sync_ptr(snd_pcm_hw_t *hw, unsigned int flags)
return 0;
}
static int request_hwsync(snd_pcm_hw_t *hw)
{
if (!hw->mmap_status_fallbacked)
return 0;
/*
* Query both of control/status data to avoid unexpected change of
* control data in kernel space.
*/
return sync_ptr1(hw,
SNDRV_PCM_SYNC_PTR_HWSYNC |
SNDRV_PCM_SYNC_PTR_APPL |
SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
}
static int query_status_and_control_data(snd_pcm_hw_t *hw)
{
if (!hw->mmap_control_fallbacked)
@ -593,8 +608,8 @@ static int snd_pcm_hw_hwsync(snd_pcm_t *pcm)
snd_pcm_hw_t *hw = pcm->private_data;
int fd = hw->fd, err;
if (SNDRV_PROTOCOL_VERSION(2, 0, 3) <= hw->version) {
if (hw->sync_ptr) {
err = sync_ptr1(hw, SNDRV_PCM_SYNC_PTR_HWSYNC);
if (hw->mmap_status_fallbacked) {
err = request_hwsync(hw);
if (err < 0)
return err;
} else {