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authorClemens Ladisch <clemens@ladisch.de>2005-05-13 07:50:28 +0200
committerJaroslav Kysela <perex@suse.cz>2005-05-29 10:08:53 +0200
commit29b16931f936fdbcd78995e66d0f5626f3afbda8 (patch)
tree938e0d682b0977d093690481a842132fb5a22718 /sound/usb
parent50cdbf1519a891bec4ce306c7bae397a0d8e7246 (diff)
downloadop-kernel-dev-29b16931f936fdbcd78995e66d0f5626f3afbda8.zip
op-kernel-dev-29b16931f936fdbcd78995e66d0f5626f3afbda8.tar.gz
[ALSA] usb-audio - avoid unnecessary double buffering
USB generic driver When a USB packet boundary falls exactly on a buffer boundary, hwptr remains at the end of the buffer which causes an overflow in the next iteration and triggers double buffering although the next packet would actually be contiguous. This patch ensures that hwptr is always smaller than buffer_size. Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/usbaudio.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index a6ed0d0..076da19 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -565,6 +565,8 @@ static int prepare_playback_urb(snd_usb_substream_t *subs,
/* set the buffer pointer */
urb->transfer_buffer = runtime->dma_area + subs->hwptr * stride;
subs->hwptr += offs;
+ if (subs->hwptr == runtime->buffer_size)
+ subs->hwptr = 0;
}
spin_unlock_irqrestore(&subs->lock, flags);
urb->transfer_buffer_length = offs * stride;
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