From fd5723b385557bc77b93dfe5ab591813407686c0 Mon Sep 17 00:00:00 2001 From: Wu Fengguang Date: Wed, 29 Sep 2010 12:18:41 +0800 Subject: pulse-audio: fix bug on updating rpos Fix a rpos coordination bug between qpa_run_out() and qpa_thread_out(), which shows up as playback noises. qpa_run_out() qpa_thread_out loop N critical section 1 qpa_run_out() qpa_thread_out loop N doing pa_simple_write() qpa_run_out() qpa_thread_out loop N doing pa_simple_write() qpa_thread_out loop N critical section 2 qpa_thread_out loop N+1 critical section 1 qpa_run_out() qpa_thread_out loop N+1 doing pa_simple_write() In the above scheme, "qpa_thread_out loop N+1 critical section 1" will get the same rpos as the one used by "qpa_thread_out loop N critical section 1". So it will be reading dead samples from the old rpos. The rpos can only be updated back to qpa_thread_out when there is a qpa_run_out() run between two qpa_thread_out loops. normal sequence: qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1) qpa_run_out: pa->rpos (X1) => hw->rpos (X1) qpa_thread_out: hw->rpos (X1) => local rpos => pa->rpos (X2) buggy sequence: qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1) qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1') Obviously qpa_run_out() shall be called at least once between any two qpa_thread_out loops (after pa->rpos is set), in order for the new qpa_thread_out loop to see the updated rpos. Setting pa->live to 0 does the trick. The next loop will have to wait for one qpa_run_out() invocation in order to get a non-zero pa->live and proceed. Signed-off-by: malc Signed-off-by: Wu Fengguang --- audio/paaudio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'audio') diff --git a/audio/paaudio.c b/audio/paaudio.c index 9118ece40c..ff71dac2a5 100644 --- a/audio/paaudio.c +++ b/audio/paaudio.c @@ -110,8 +110,8 @@ static void *qpa_thread_out (void *arg) return NULL; } + pa->live = 0; pa->rpos = rpos; - pa->live -= decr; pa->decr += decr; } -- cgit v1.2.1