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pcm: hw: add a helper function to query status/control data

Browse source 
When executing ioctl(2) with some commands, applications can request
ALSA PCM core to change appl_ptr in kernel space. Below is a list of
such operations:
 - SNDRV_PCM_IOCTL_PREPARE
 - SNDRV_PCM_IOCTL_RESET
 - SNDRV_PCM_IOCTL_REWIND
 - SNDRV_PCM_IOCTL_FORWARD
 - SNDRV_PCM_IOCTL_WRITEI_FRAMES
 - SNDRV_PCM_IOCTL_WRITEN_FRAMES
 - SNDRV_PCM_IOCTL_READI_FRAMES
 - SNDRV_PCM_IOCTL_READN_FRAMES

After these operations, the value of appl_ptr should be synchronized
between kernel/user spaces.

This commit adds a helper function to query status and control data
without issuing the control data just in fallback from failure of control
mapping.

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 20:37:24 +09:00 • committed by Takashi Iwai
parent 4396c83a4d
commit ce0905c3ca
1 changed files with 34 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

46
src/pcm/pcm_hw.c
View file

@ -151,6 +151,20 @@ static int sync_ptr(snd_pcm_hw_t *hw, unsigned int flags)
return 0;
}
static int query_status_and_control_data(snd_pcm_hw_t *hw)
{
if (!hw->mmap_control_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_APPL |
SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
}
static int snd_pcm_hw_clear_timer_queue(snd_pcm_hw_t *hw)
{
if (hw->period_timer_need_poll) {
@ -601,7 +615,7 @@ static int snd_pcm_hw_prepare(snd_pcm_t *pcm)
SYSMSG("SNDRV_PCM_IOCTL_PREPARE failed (%i)", err);
return err;
}
return sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL);
return query_status_and_control_data(hw);
}
static int snd_pcm_hw_reset(snd_pcm_t *pcm)
@ -613,7 +627,7 @@ static int snd_pcm_hw_reset(snd_pcm_t *pcm)
SYSMSG("SNDRV_PCM_IOCTL_RESET failed (%i)", err);
return err;
}
return sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL);
return query_status_and_control_data(hw);
}
static int snd_pcm_hw_start(snd_pcm_t *pcm)
@ -688,7 +702,7 @@ static snd_pcm_sframes_t snd_pcm_hw_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t fra
SYSMSG("SNDRV_PCM_IOCTL_REWIND failed (%i)", err);
return err;
}
err = sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL);
err = query_status_and_control_data(hw);
if (err < 0)
return err;
return frames;
@ -709,7 +723,7 @@ static snd_pcm_sframes_t snd_pcm_hw_forward(snd_pcm_t *pcm, snd_pcm_uframes_t fr
SYSMSG("SNDRV_PCM_IOCTL_FORWARD failed (%i)", err);
return err;
}
err = sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL);
err = query_status_and_control_data(hw);
if (err < 0)
return err;
return frames;
@ -805,8 +819,10 @@ static snd_pcm_sframes_t snd_pcm_hw_writei(snd_pcm_t *pcm, const void *buffer, s
xferi.buf = (char*) buffer;
xferi.frames = size;
xferi.result = 0; /* make valgrind happy */
err = ioctl(fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &xferi);
err = err >= 0 ? sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL) : -errno;
if (ioctl(fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &xferi) < 0)
err = -errno;
else
err = query_status_and_control_data(hw);
#ifdef DEBUG_RW
fprintf(stderr, "hw_writei: frames = %li, xferi.result = %li, err = %i\n", size, xferi.result, err);
#endif
@ -824,8 +840,10 @@ static snd_pcm_sframes_t snd_pcm_hw_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_
memset(&xfern, 0, sizeof(xfern)); /* make valgrind happy */
xfern.bufs = bufs;
xfern.frames = size;
err = ioctl(fd, SNDRV_PCM_IOCTL_WRITEN_FRAMES, &xfern);
err = err >= 0 ? sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL) : -errno;
if (ioctl(fd, SNDRV_PCM_IOCTL_WRITEN_FRAMES, &xfern) < 0)
err = -errno;
else
err = query_status_and_control_data(hw);
#ifdef DEBUG_RW
fprintf(stderr, "hw_writen: frames = %li, result = %li, err = %i\n", size, xfern.result, err);
#endif
@ -843,8 +861,10 @@ static snd_pcm_sframes_t snd_pcm_hw_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_
xferi.buf = buffer;
xferi.frames = size;
xferi.result = 0; /* make valgrind happy */
err = ioctl(fd, SNDRV_PCM_IOCTL_READI_FRAMES, &xferi);
err = err >= 0 ? sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL) : -errno;
if (ioctl(fd, SNDRV_PCM_IOCTL_READI_FRAMES, &xferi) < 0)
err = -errno;
else
err = query_status_and_control_data(hw);
#ifdef DEBUG_RW
fprintf(stderr, "hw_readi: frames = %li, result = %li, err = %i\n", size, xferi.result, err);
#endif
@ -862,8 +882,10 @@ static snd_pcm_sframes_t snd_pcm_hw_readn(snd_pcm_t *pcm, void **bufs, snd_pcm_u
memset(&xfern, 0, sizeof(xfern)); /* make valgrind happy */
xfern.bufs = bufs;
xfern.frames = size;
err = ioctl(fd, SNDRV_PCM_IOCTL_READN_FRAMES, &xfern);
err = err >= 0 ? sync_ptr(hw, SNDRV_PCM_SYNC_PTR_APPL) : -errno;
if (ioctl(fd, SNDRV_PCM_IOCTL_READN_FRAMES, &xfern) < 0)
err = -errno;
else
err = query_status_and_control_data(hw);
#ifdef DEBUG_RW
fprintf(stderr, "hw_readn: frames = %li, result = %li, err = %i\n", size, xfern.result, err);
#endif