ALSA: firewire-lib: optimize packet flushing
Trying to flush completed packets is pointless when the pointer
callback was called from the packet completion callback; avoid it.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index c2685fb..ea995af 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -178,6 +178,7 @@
tasklet_kill(&s->period_tasklet);
s->pcm_buffer_pointer = 0;
s->pcm_period_pointer = 0;
+ s->pointer_flush = true;
}
EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare);
@@ -393,6 +394,7 @@
s->pcm_period_pointer += data_blocks;
if (s->pcm_period_pointer >= pcm->runtime->period_size) {
s->pcm_period_pointer -= pcm->runtime->period_size;
+ s->pointer_flush = false;
tasklet_hi_schedule(&s->period_tasklet);
}
}
@@ -539,7 +541,11 @@
*/
unsigned long amdtp_out_stream_pcm_pointer(struct amdtp_out_stream *s)
{
- fw_iso_context_flush_completions(s->context);
+ /* this optimization is allowed to be racy */
+ if (s->pointer_flush)
+ fw_iso_context_flush_completions(s->context);
+ else
+ s->pointer_flush = true;
return ACCESS_ONCE(s->pcm_buffer_pointer);
}
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h
index 3f13ff6..b680c5e 100644
--- a/sound/firewire/amdtp.h
+++ b/sound/firewire/amdtp.h
@@ -68,6 +68,7 @@
unsigned int pcm_buffer_pointer;
unsigned int pcm_period_pointer;
+ bool pointer_flush;
};
int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,