From: Vanitha Channaiah vanitha.channaiah@in.bosch.com
This change adapt the fix commit 6b058fda9dce ("pcm: dmix: Add option to allow alignment of slave pointers") for dsnoop plugin
Issue is that snd_pcm_wait() goes back to waiting because the hw_ptr is not period aligned. Therefore snd_pcm_wait() will block for a longer time as required.
With these rcar driver changes the exact position of the dma is returned. During snd_pcm_start they read hw_ptr as reference, and this hw_ptr is now not period aligned, and is a little ahead over the period while it is read. Therefore when the avail is calculated during snd_pcm_wait(), it is missing the avail_min by a few frames.
An additional option hw_ptr_alignment is provided to dsnoop configuration, to allow the user to configure the slave application and hw pointer alignment at startup
Signed-off-by: Vanitha Channaiah vanitha.channaiah@in.bosch.com --- src/pcm/pcm_direct.c | 1 - src/pcm/pcm_dmix.c | 2 ++ src/pcm/pcm_dshare.c | 2 ++ src/pcm/pcm_dsnoop.c | 30 +++++++++++++++++++++++++++++- 4 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/src/pcm/pcm_direct.c b/src/pcm/pcm_direct.c index 411a035..54d9900 100644 --- a/src/pcm/pcm_direct.c +++ b/src/pcm/pcm_direct.c @@ -2043,7 +2043,6 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf,
void snd_pcm_direct_reset_slave_ptr(snd_pcm_t *pcm, snd_pcm_direct_t *dmix) { - dmix->slave_appl_ptr = dmix->slave_hw_ptr = *dmix->spcm->hw.ptr;
if (dmix->hw_ptr_alignment == SND_PCM_HW_PTR_ALIGNMENT_ROUNDUP || (dmix->hw_ptr_alignment == SND_PCM_HW_PTR_ALIGNMENT_AUTO && diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c index dcde40d..274726e 100644 --- a/src/pcm/pcm_dmix.c +++ b/src/pcm/pcm_dmix.c @@ -562,6 +562,7 @@ static int snd_pcm_dmix_reset(snd_pcm_t *pcm) snd_pcm_direct_t *dmix = pcm->private_data; dmix->hw_ptr %= pcm->period_size; dmix->appl_ptr = dmix->last_appl_ptr = dmix->hw_ptr; + dmix->slave_appl_ptr = dmix->slave_hw_ptr = *dmix->spcm->hw.ptr; snd_pcm_direct_reset_slave_ptr(pcm, dmix); return 0; } @@ -571,6 +572,7 @@ static int snd_pcm_dmix_start_timer(snd_pcm_t *pcm, snd_pcm_direct_t *dmix) int err;
snd_pcm_hwsync(dmix->spcm); + dmix->slave_appl_ptr = dmix->slave_hw_ptr = *dmix->spcm->hw.ptr; snd_pcm_direct_reset_slave_ptr(pcm, dmix); err = snd_timer_start(dmix->timer); if (err < 0) diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c index cf8a863..b75809c 100644 --- a/src/pcm/pcm_dshare.c +++ b/src/pcm/pcm_dshare.c @@ -333,6 +333,7 @@ static int snd_pcm_dshare_reset(snd_pcm_t *pcm) snd_pcm_direct_t *dshare = pcm->private_data; dshare->hw_ptr %= pcm->period_size; dshare->appl_ptr = dshare->last_appl_ptr = dshare->hw_ptr; + dshare->slave_appl_ptr = dshare->slave_hw_ptr = *dshare->spcm->hw.ptr; snd_pcm_direct_reset_slave_ptr(pcm, dshare); return 0; } @@ -342,6 +343,7 @@ static int snd_pcm_dshare_start_timer(snd_pcm_t *pcm, snd_pcm_direct_t *dshare) int err;
snd_pcm_hwsync(dshare->spcm); + dshare->slave_appl_ptr = dshare->slave_hw_ptr = *dshare->spcm->hw.ptr; snd_pcm_direct_reset_slave_ptr(pcm, dshare); err = snd_timer_start(dshare->timer); if (err < 0) diff --git a/src/pcm/pcm_dsnoop.c b/src/pcm/pcm_dsnoop.c index d08b624..58b1e53 100644 --- a/src/pcm/pcm_dsnoop.c +++ b/src/pcm/pcm_dsnoop.c @@ -278,6 +278,7 @@ static int snd_pcm_dsnoop_reset(snd_pcm_t *pcm) dsnoop->hw_ptr %= pcm->period_size; dsnoop->appl_ptr = dsnoop->hw_ptr; dsnoop->slave_appl_ptr = dsnoop->slave_hw_ptr; + snd_pcm_direct_reset_slave_ptr(pcm, dsnoop); return 0; }
@@ -285,12 +286,13 @@ static int snd_pcm_dsnoop_start(snd_pcm_t *pcm) { snd_pcm_direct_t *dsnoop = pcm->private_data; int err; - + if (dsnoop->state != SND_PCM_STATE_PREPARED) return -EBADFD; snd_pcm_hwsync(dsnoop->spcm); snoop_timestamp(pcm); dsnoop->slave_appl_ptr = dsnoop->slave_hw_ptr; + snd_pcm_direct_reset_slave_ptr(pcm, dsnoop); err = snd_timer_start(dsnoop->timer); if (err < 0) return err; @@ -627,6 +629,7 @@ int snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name, dsnoop->max_periods = opts->max_periods; dsnoop->var_periodsize = opts->var_periodsize; dsnoop->sync_ptr = snd_pcm_dsnoop_sync_ptr; + dsnoop->hw_ptr_alignment = opts->hw_ptr_alignment;
retry: if (first_instance) { @@ -771,6 +774,12 @@ pcm.name { ipc_key INT # unique IPC key ipc_key_add_uid BOOL # add current uid to unique IPC key ipc_perm INT # IPC permissions (octal, default 0600) + hw_ptr_alignment STR # Slave application and hw pointer alignment type + # STR can be one of the below strings : + # no + # roundup + # rounddown + # auto (default) slave STR # or slave { # Slave definition @@ -795,6 +804,25 @@ pcm.name { } \endcode
+<code>hw_ptr_alignment</code> specifies slave application and hw +pointer alignment type. By default hw_ptr_alignment is auto. Below are +the possible configurations: +- no: minimal latency with minimal frames dropped at startup. But + wakeup of application (return from snd_pcm_wait() or poll()) can + take up to 2 * period. +- roundup: It is guaranteed that all frames will be played at + startup. But the latency will increase upto period-1 frames. +- rounddown: It is guaranteed that a wakeup will happen for each + period and frames can be written from application. But on startup + upto period-1 frames will be dropped. +- auto: Selects the best approach depending on the used period and + buffer size. + If the application buffer size is < 2 * application period, + "roundup" will be selected to avoid over runs. If the slave_period + is < 10ms we could expect that there are low latency + requirements. Therefore "rounddown" will be chosen to avoid long + wakeup times. Else "no" will be chosen. + \subsection pcm_plugins_dsnoop_funcref Function reference
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