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[media] em28xx: fix wrong data offset for non-interlaced mode in em28xx_copy_video 

em28xx_copy_video uses a wrong offset for the target buffer
when copying the data from an USB isoc packet. This happens
only for the second and all following lines in the packet.
The reason why this bug doesn't cause image corruption with
my test device (SilverCrest Webcam 1.3 MPix) is, that this
device never sends any packets that cross the end of a line.
I don't know if all devices behave like this, so this patch
should be considered for stable.
With the upcoming patches to add support for USB bulk transfers,
em28xx_copy_video will be called once per URB, which will
always trigger this bug.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Frank Schaefer 2012-11-08 14:11:33 -03:00 committed by Mauro Carvalho Chehab
parent 2f5741aa6a
commit c02ec71b01
1 changed files with 7 additions and 9 deletions
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16
drivers/media/usb/em28xx/em28xx-video.c
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@ -207,15 +207,10 @@ static void em28xx_copy_video(struct em28xx *dev,
startread = p;
remain = len;
if (dev->progressive)
if (dev->progressive || buf->top_field)
fieldstart = outp;
else {
/* Interlaces two half frames */
if (buf->top_field)
fieldstart = outp;
else
fieldstart = outp + bytesperline;
}
else /* interlaced mode, even nr. of lines */
fieldstart = outp + bytesperline;
linesdone = dma_q->pos / bytesperline;
currlinedone = dma_q->pos % bytesperline;
@ -243,7 +238,10 @@ static void em28xx_copy_video(struct em28xx *dev,
remain -= lencopy;
while (remain > 0) {
startwrite += lencopy + bytesperline;
if (dev->progressive)
startwrite += lencopy;
else
startwrite += lencopy + bytesperline;
startread += lencopy;
if (bytesperline > remain)
lencopy = remain;