From bd76af0f87f7a1815b311bde269a3f18305b3169 Mon Sep 17 00:00:00 2001 From: Jaroslav Kysela Date: Wed, 18 Aug 2010 14:16:54 +0200 Subject: 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 Signed-off-by: Takashi Iwai --- sound/core/pcm_lib.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'sound/core/pcm_lib.c') diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index e23e0e7..a1707cc 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 */ -- cgit v1.1