From c02ec71b014ea7bc6f50deb9db765bf57d593c53 Mon Sep 17 00:00:00 2001 From: Frank Schaefer Date: Thu, 8 Nov 2012 14:11:33 -0300 Subject: [PATCH] [media] em28xx: fix wrong data offset for non-interlaced mode in em28xx_copy_video MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/usb/em28xx/em28xx-video.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c index 766ad125fc08..202e00bb2b6e 100644 --- a/drivers/media/usb/em28xx/em28xx-video.c +++ b/drivers/media/usb/em28xx/em28xx-video.c @@ -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; -- 2.20.1