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

Browse Source 
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
View File

@ -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;

39
sound/core/pcm_native.c
View File

@ -27,7 +27,6 @@
#include <linux/pm_qos_params.h>
#include <linux/uio.h>
#include <linux/dma-mapping.h>
#include <linux/math64.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>
@ -370,38 +369,6 @@ static int period_to_usecs(struct snd_pcm_runtime *runtime)
return usecs;
}
static int calc_boundary(struct snd_pcm_runtime *runtime)
{
u_int64_t boundary;
boundary = (u_int64_t)runtime->buffer_size *
(u_int64_t)runtime->period_size;
#if BITS_PER_LONG < 64
/* try to find lowest common multiple for buffer and period */
if (boundary > LONG_MAX - runtime->buffer_size) {
u_int32_t remainder = -1;
u_int32_t divident = runtime->buffer_size;
u_int32_t divisor = runtime->period_size;
while (remainder) {
remainder = divident % divisor;
if (remainder) {
divident = divisor;
divisor = remainder;
}
}
boundary = div_u64(boundary, divisor);
if (boundary > LONG_MAX - runtime->buffer_size)
return -ERANGE;
}
#endif
if (boundary == 0)
return -ERANGE;
runtime->boundary = boundary;
while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
runtime->boundary *= 2;
return 0;
}
static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
@ -477,9 +444,9 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
runtime->stop_threshold = runtime->buffer_size;
runtime->silence_threshold = 0;
runtime->silence_size = 0;
err = calc_boundary(runtime);
if (err < 0)
goto _error;
runtime->boundary = runtime->buffer_size;
while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
runtime->boundary *= 2;
snd_pcm_timer_resolution_change(substream);
runtime->status->state = SNDRV_PCM_STATE_SETUP;