ALSA: pcm_lib - return back hw_ptr_interrupt
Clemens Ladisch noted for hw_ptr_removal in "cleanup & merge hw_ptr
update functions" commit:
"It is possible for the status/delay ioctls to be called when the sound
card's pointer register alreay shows a position at the beginning of the
new period, but immediately before the interrupt is actually executed.
(This happens regularly on a SMP machine with mplayer.) When that
happens, the code thinks that the position must be at least one period
ahead of the current position and drops an entire buffer of data."
Return back the hw_ptr_interrupt variable. The last interrupt pointer
is always computed from the latest hw_ptr instead of tracking it
separately (in this case all hw_ptr checks and modifications might
influence also hw_ptr_interrupt and it is difficult to keep it
consistent).
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 3bc9bca..13bc83c 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -271,6 +271,7 @@
int overrange;
snd_pcm_uframes_t avail_max;
snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */
+ snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
unsigned long hw_ptr_jiffies; /* Time when hw_ptr is updated */
snd_pcm_sframes_t delay; /* extra delay; typically FIFO size */
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 255ad91..82d4e33 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -635,8 +635,7 @@
static inline
snd_pcm_uframes_t get_hw_ptr_period(struct snd_pcm_runtime *runtime)
{
- snd_pcm_uframes_t ptr = runtime->status->hw_ptr;
- return ptr - (ptr % runtime->period_size);
+ return runtime->hw_ptr_interrupt;
}
/* define extended formats in the recent OSS versions (if any) */
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index e2a817e..aa54195 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -325,8 +325,7 @@
if (in_interrupt) {
/* we know that one period was processed */
/* delta = "expected next hw_ptr" for in_interrupt != 0 */
- delta = old_hw_ptr - (old_hw_ptr % runtime->period_size)
- + runtime->period_size;
+ delta = runtime->hw_ptr_interrupt + runtime->period_size;
if (delta > new_hw_ptr) {
hw_base += runtime->buffer_size;
if (hw_base >= runtime->boundary)
@@ -437,6 +436,10 @@
runtime->silence_size > 0)
snd_pcm_playback_silence(substream, new_hw_ptr);
+ if (in_interrupt) {
+ runtime->hw_ptr_interrupt = new_hw_ptr -
+ (new_hw_ptr % runtime->period_size);
+ }
runtime->hw_ptr_base = hw_base;
runtime->status->hw_ptr = new_hw_ptr;
runtime->hw_ptr_jiffies = jiffies;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 56ec35e..7a002db 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1252,6 +1252,8 @@
if (err < 0)
return err;
runtime->hw_ptr_base = 0;
+ runtime->hw_ptr_interrupt = runtime->status->hw_ptr -
+ runtime->status->hw_ptr % runtime->period_size;
runtime->silence_start = runtime->status->hw_ptr;
runtime->silence_filled = 0;
return 0;