On 2014-11-12 14:15, Peter Meerwald wrote:
From: Peter Meerwald <p.meerw...@bct-electronic.com>
snd_pcm_mmap_commit() actually transfers the memory area prepared by
snd_pcm_mmap_begin(),
it returns the 'count of transferred frames' which should be equal to the
number of frames
returned by snd_pcm_mmap_begin()
however, this identify is not checked and the number of frames prepared are
accounted for,
not the number of frames commited -- this is wrong; the ALSA example codes
bothers to
check snd_pcm_mmap_commit()'s returned number of frames
this patch outputs a warning and uses the commited number of frames to update
the bytes
read or written, resp.
It's not that easy, I think...
In case you get fewer frames written, you should retry the mmap_begin +
mmap_commit cycle but *without* calling pa_sink_render_into_full, and
only with the remaining frames. Right?
Signed-off-by: Peter Meerwald <pme...@pmeerw.net>
---
src/modules/alsa/alsa-sink.c | 11 +++++++++--
src/modules/alsa/alsa-source.c | 17 +++++++++++++----
2 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
index e256bbd..fc05232 100644
--- a/src/modules/alsa/alsa-sink.c
+++ b/src/modules/alsa/alsa-sink.c
@@ -639,8 +639,7 @@ static int mmap_write(struct userdata *u, pa_usec_t
*sleep_usec, bool polled, bo
p = (uint8_t*) areas[0].addr + (offset * u->frame_size);
- written = frames * u->frame_size;
- chunk.memblock = pa_memblock_new_fixed(u->core->mempool, p,
written, true);
+ chunk.memblock = pa_memblock_new_fixed(u->core->mempool, p, frames *
u->frame_size, true);
chunk.length = pa_memblock_get_length(chunk.memblock);
chunk.index = 0;
@@ -660,6 +659,14 @@ static int mmap_write(struct userdata *u, pa_usec_t
*sleep_usec, bool polled, bo
work_done = true;
+ if (PA_UNLIKELY((snd_pcm_uframes_t) sframes != frames)) {
+ PA_ONCE_BEGIN {
+ pa_log_warn("ALSA mmap write was set up up for %lu frames, but
unexpectedly commited %lu frames.\n",
+ (unsigned long) frames, (unsigned long) sframes);
+ } PA_ONCE_END;
+ }
+
+ written = sframes * u->frame_size;
u->write_count += written;
u->since_start += written;
diff --git a/src/modules/alsa/alsa-source.c b/src/modules/alsa/alsa-source.c
index 111c517..36e7585 100644
--- a/src/modules/alsa/alsa-source.c
+++ b/src/modules/alsa/alsa-source.c
@@ -562,6 +562,7 @@ static int mmap_read(struct userdata *u, pa_usec_t
*sleep_usec, bool polled, boo
const snd_pcm_channel_area_t *areas;
snd_pcm_uframes_t offset, frames;
snd_pcm_sframes_t sframes;
+ size_t got;
frames = (snd_pcm_uframes_t) (n_bytes / u->frame_size);
/* pa_log_debug("%lu frames to read", (unsigned long) frames); */
@@ -613,16 +614,24 @@ static int mmap_read(struct userdata *u, pa_usec_t
*sleep_usec, bool polled, boo
work_done = true;
- u->read_count += frames * u->frame_size;
+ if (PA_UNLIKELY((snd_pcm_uframes_t) sframes != frames)) {
+ PA_ONCE_BEGIN {
+ pa_log_warn("ALSA mmap read was set up up for %lu frames, but
unexpectedly commited %lu frames.\n",
+ (unsigned long) frames, (unsigned long) sframes);
+ } PA_ONCE_END;
+ }
+
+ got = sframes * u->frame_size;
+ u->read_count += got;
#ifdef DEBUG_TIMING
- pa_log_debug("Read %lu bytes (of possible %lu bytes)", (unsigned
long) (frames * u->frame_size), (unsigned long) n_bytes);
+ pa_log_debug("Read %lu bytes (of possible %lu bytes)", (unsigned
long) got, (unsigned long) n_bytes);
#endif
- if ((size_t) frames * u->frame_size >= n_bytes)
+ if (got >= n_bytes)
break;
- n_bytes -= (size_t) frames * u->frame_size;
+ n_bytes -= got;
}
}
--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
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