[3.13.y.z extended stable] Patch "ALSA: pcm: fix fifo_size frame calculation" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu Oct 9 20:51:45 UTC 2014

This is a note to let you know that I have just added a patch titled

    ALSA: pcm: fix fifo_size frame calculation

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From 0b73113f217cf16d7f69de9bf40c550606296c5b Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens at ladisch.de>
Date: Sun, 21 Sep 2014 22:50:57 +0200
Subject: ALSA: pcm: fix fifo_size frame calculation

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 at ladisch.de>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 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 a210467..e1ef106 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1783,14 +1783,16 @@ 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;

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