ALSA: pcm: fix fifo_size frame calculation

[Clemens Ladisch]

The calculated frame size was wrong because snd_pcm_format_physical_width()
actually returns the number of bits, not bytes.

Use snd_pcm_format_size() instead, which not only returns bytes, but also
simplifies the calculation.

Fixes: 8bea869c5e56 ("ALSA: PCM midlevel: improve fifo_size handling")
Signed-off-by: Clemens Ladisch <***@ladisch.de>
---
sound/core/pcm_lib.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index b03c7ae..dfc2854 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1784,14 +1784,16 @@ static int snd_pcm_lib_ioctl_fifo_size(struct snd_pcm_substream *substream,
{
struct snd_pcm_hw_params *params = arg;
snd_pcm_format_t format;
- int channels, width;
+ int channels;
+ ssize_t frame_size;

params->fifo_size = substream->runtime->hw.fifo_size;
if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_FIFO_IN_FRAMES)) {
format = params_format(params);
channels = params_channels(params);
- width = snd_pcm_format_physical_width(format);
- params->fifo_size /= width * channels;
+ frame_size = snd_pcm_format_size(format, channels);
+ if (frame_size > 0)
+ params->fifo_size /= (unsigned)frame_size;
}
return 0;
}

[Takashi Iwai]

At Sun, 21 Sep 2014 22:50:57 +0200,

Post by Clemens Ladisch
The calculated frame size was wrong because snd_pcm_format_physical_width()
actually returns the number of bits, not bytes.
Use snd_pcm_format_size() instead, which not only returns bytes, but also
simplifies the calculation.
Fixes: 8bea869c5e56 ("ALSA: PCM midlevel: improve fifo_size handling")

Thanks, applied now. I put Cc to stable as this is a clear bug fix.


Takashi

Post by Clemens Ladisch
---
sound/core/pcm_lib.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index b03c7ae..dfc2854 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1784,14 +1784,16 @@ static int snd_pcm_lib_ioctl_fifo_size(struct snd_pcm_substream *substream,
{
struct snd_pcm_hw_params *params = arg;
snd_pcm_format_t format;
- int channels, width;
+ int channels;
+ ssize_t frame_size;
params->fifo_size = substream->runtime->hw.fifo_size;
if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_FIFO_IN_FRAMES)) {
format = params_format(params);
channels = params_channels(params);
- width = snd_pcm_format_physical_width(format);
- params->fifo_size /= width * channels;
+ frame_size = snd_pcm_format_size(format, channels);
+ if (frame_size > 0)
+ params->fifo_size /= (unsigned)frame_size;
}
return 0;
}