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authorJaroslav Kysela <perex@perex.cz>2010-08-18 14:16:54 +0200
committerTakashi Iwai <tiwai@suse.de>2010-08-18 15:18:02 +0200
commitbd76af0f87f7a1815b311bde269a3f18305b3169 (patch)
tree27f95b3e568146eed0958989f3f8d0c4eae3616b /sound/core
parente7cfbea9cb7a02ea29fdae5d39c9e3d09102c4d5 (diff)
ALSA: pcm midlevel code - add time check for double interrupt acknowledge
The current code in pcm_lib.c do all checks using only the position in the ring buffer. Unfortunately, where the interrupts gets delayed or merged into one, we need another timing source to check when the buffer size boundary overlaps to avoid the wrong updating of the ring buffer pointers. This code uses jiffies to check the right time window without any performance impact. Signed-off-by: Jaroslav Kysela <perex@perex.cz> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/pcm_lib.c14
-rw-r--r--sound/core/pcm_native.c2
2 files changed, 11 insertions, 5 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index e23e0e7ab26..a1707cca9c6 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -334,11 +334,15 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
/* delta = "expected next hw_ptr" for in_interrupt != 0 */
delta = runtime->hw_ptr_interrupt + runtime->period_size;
if (delta > new_hw_ptr) {
- hw_base += runtime->buffer_size;
- if (hw_base >= runtime->boundary)
- hw_base = 0;
- new_hw_ptr = hw_base + pos;
- goto __delta;
+ /* check for double acknowledged interrupts */
+ hdelta = jiffies - runtime->hw_ptr_jiffies;
+ if (hdelta > runtime->hw_ptr_buffer_jiffies/2) {
+ hw_base += runtime->buffer_size;
+ if (hw_base >= runtime->boundary)
+ hw_base = 0;
+ new_hw_ptr = hw_base + pos;
+ goto __delta;
+ }
}
}
/* new_hw_ptr might be lower than old_hw_ptr in case when */
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 134fc6c2e08..e2e73895db1 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -864,6 +864,8 @@ static void snd_pcm_post_start(struct snd_pcm_substream *substream, int state)
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_trigger_tstamp(substream);
runtime->hw_ptr_jiffies = jiffies;
+ runtime->hw_ptr_buffer_jiffies = (runtime->buffer_size * HZ) /
+ runtime->rate;
runtime->status->state = state;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
runtime->silence_size > 0)