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ALSA: pcm: fix the fix of the runtime->boundary calculation

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Commit 7910b4a1db in 2.6.34 changed the
runtime->boundary calculation to make this value a multiple of both the
buffer_size and the period_size, because the latter is assumed by the
runtime->hw_ptr_interrupt calculation.

However, due to the lack of a ioctl that could read the software
parameters before they are set, the kernel requires that alsa-lib
calculates the boundary value, too.  The changed algorithm leads to
a different boundary value used by alsa-lib, which makes, e.g., mplayer
fail to play a 44.1 kHz file because the silence_size parameter is now
invalid; bug report:
<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=5015>.

This patch reverts the change to the boundary calculation, and instead
fixes the hw_ptr_interrupt calculation to be period-aligned regardless
of the boundary value.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch
2010-05-21 09:15:59 +02:00
committed by Takashi Iwai
parent 7f06a8b26a
commit ead4046b2f
2 changed files with 10 additions and 38 deletions
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9
sound/core/pcm_lib.c
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@ -439,8 +439,13 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
snd_pcm_playback_silence(substream, new_hw_ptr);
if (in_interrupt) {
runtime->hw_ptr_interrupt = new_hw_ptr -
(new_hw_ptr % runtime->period_size);
delta = new_hw_ptr - runtime->hw_ptr_interrupt;
if (delta < 0)
delta += runtime->boundary;
delta -= (snd_pcm_uframes_t)delta % runtime->period_size;
runtime->hw_ptr_interrupt += delta;
if (runtime->hw_ptr_interrupt >= runtime->boundary)
runtime->hw_ptr_interrupt -= runtime->boundary;
}
runtime->hw_ptr_base = hw_base;
runtime->status->hw_ptr = new_hw_ptr;