ALSA: pcm: fix fifo_size frame calculation

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: 8bea869c ("ALSA: PCM midlevel: improve fifo_size handling")
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm_lib.c

@@ -1782,14 +1782,16 @@ 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;
 }