Commit 3e5b5016 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm core - Avoid jiffies check for devices with BATCH flag

The hardware devices with SNDRV_PCM_INFO_BATCH flag can't give the
precise current position.  And such hardwares have often big FIFO
in addition to the ring buffer, and it screws up the jiffies check
in pcm_lib.c.

This patch adds a simple check of info flag so that the driver skips
the jiffies check in snd_pcm_period_elapsed() when BATCH flag is set.

Signed-off-by: default avatarTakashi Iwai <>
parent 2008f137
......@@ -249,6 +249,12 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
new_hw_ptr = hw_base + pos;
/* Skip the jiffies check for hardwares with BATCH flag.
* Such hardware usually just increases the position at each IRQ,
* thus it can't give any strange position.
if (runtime-> & SNDRV_PCM_INFO_BATCH)
goto no_jiffies_check;
hdelta = new_hw_ptr - old_hw_ptr;
jdelta = jiffies - runtime->hw_ptr_jiffies;
if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
......@@ -272,6 +278,7 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
hw_base -= hw_base % runtime->buffer_size;
delta = 0;
if (delta > runtime->period_size + runtime->period_size / 2) {
"Lost interrupts? "
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment