[PATCH 3.2 066/102] ALSA: pcm: fix fifo_size frame calculation

From: Ben Hutchings
Date: Sat Nov 01 2014 - 18:59:41 EST


3.2.64-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Clemens Ladisch <clemens@xxxxxxxxxx>

commit a9960e6a293e6fc3ed414643bb4e4106272e4d0a upstream.

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 <clemens@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
sound/core/pcm_lib.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1692,14 +1692,16 @@ static int snd_pcm_lib_ioctl_fifo_size(s
{
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;
}

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