2010-09-01 20:06, pl bossart skrev:
>>> Probably either one will work, but if we're about to release 0.9.22
>>> (heard something from Lennart yet?), I suggest we go with my version for
>>> 0.9.22 as that one is the least invasive (only touches non-tsched
>>> devices), and keep Pierre's version in master.
>>
>> Sounds reasonable. Pierre, what's your take?
>
> That would mean an additional post-release patch for tsched devices. I
> am lazy and would prefer a one-stop fix. I don't care if this is
> David's or mine, as long as the solution works for both cases.
> The only real difference is the bytes/ms parameter. Although ms are
> more intuitive, the bytes makes more sense from a hardware point of
> view. If you pass a parameter in ms, there might be cases where the
> actual number of bytes is lower than the DMA burst, it'll depend on
> what frequency the sink operates at. There are some cases where
> alsa-sink works at 8kHz (BT-SCO) or 48kHz (all other cases), a 6x
> variability in the rewind behavior is difficult to handle.
Fair enough, how about the attached compromise (untested)? If you then
would like to turn the define of dma_rewind_margin_bytes into a
parameter, that should be fairly simple.
--
David Henningsson, Canonical Ltd.
http://launchpad.net/~diwic
>From 5ae6c880e20adfa0f372f2caf293e70253651c5a Mon Sep 17 00:00:00 2001
From: David Henningsson <david.hennings...@canonical.com>
Date: Thu, 2 Sep 2010 08:22:36 +0200
Subject: [PATCH] ALSA: Fix calculation of rewind margins
For non-tsched devices, use 20 ms as a default rewind margin.
Also make sure that we have at least 256 bytes as rewind margin for
all devices, to avoid problems with DMA controllers.
Signed-off-by: David Henningsson <david.hennings...@canonical.com>
---
src/modules/alsa/alsa-sink.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
index a253cc5..097bb20 100644
--- a/src/modules/alsa/alsa-sink.c
+++ b/src/modules/alsa/alsa-sink.c
@@ -63,6 +63,9 @@
#define DEFAULT_DEVICE "default"
+#define NON_TSCHED_REWIND_MARGIN_USEC (20*PA_USEC_PER_MSEC) /* 20ms -- Default rewind margin for non-tsched devices */
+#define DMA_REWIND_MARGIN_BYTES (256) /* Make sure we're always have a rewind margin of at least 256 bytes - to avoid problems with some DMA controllers */
+
#define DEFAULT_TSCHED_BUFFER_USEC (2*PA_USEC_PER_SEC) /* 2s -- Overall buffer size */
#define DEFAULT_TSCHED_WATERMARK_USEC (20*PA_USEC_PER_MSEC) /* 20ms -- Fill up when only this much is left in the buffer */
@@ -1309,7 +1312,15 @@ static int process_rewind(struct userdata *u) {
return -1;
}
- unused_nbytes = u->tsched_watermark + (size_t) unused * u->frame_size;
+
+ if (u->use_tsched)
+ unused_nbytes = u->tsched_watermark;
+ else
+ unused_nbytes = pa_usec_to_bytes(NON_TSCHED_REWIND_MARGIN_USEC, &u->sink->sample_spec);
+ if (unused_nbytes < DMA_REWIND_MARGIN_BYTES)
+ unused_nbytes = DMA_REWIND_MARGIN_BYTES;
+
+ unused_nbytes += (size_t) unused * u->frame_size;
if (u->hwbuf_size > unused_nbytes)
limit_nbytes = u->hwbuf_size - unused_nbytes;
--
1.7.0.4
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