V4L/DVB: saa7146: fix up bytesperline if it is an impossible value

xawtv using DGA on a Radeon graphics card provides bogus
values to S_FBUF, which will then screw up overlay video:

https://bugs.launchpad.net/ubuntu/+source/xawtv/+bug/499734

This fixes the bytesperline value if it is off completely.

Signed-off-by: Michael Hunold <michael@mihu.de>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/media/common/saa7146_video.c b/drivers/media/common/saa7146_video.c
index 5ed75263340a..b8b2c551a1e2 100644
--- a/drivers/media/common/saa7146_video.c
+++ b/drivers/media/common/saa7146_video.c
@@ -558,9 +558,11 @@ static int vidioc_s_fbuf(struct file *file, void *fh, struct v4l2_framebuffer *f
         /* ok, accept it */
         vv->ov_fb = *fb;
         vv->ov_fmt = fmt;
-        if (0 == vv->ov_fb.fmt.bytesperline)
-                vv->ov_fb.fmt.bytesperline =
-                        vv->ov_fb.fmt.width * fmt->depth / 8;
+
+        if (vv->ov_fb.fmt.bytesperline < vv->ov_fb.fmt.width) {
+                vv->ov_fb.fmt.bytesperline = vv->ov_fb.fmt.width * fmt->depth / 8;
+                DEB_D(("setting bytesperline to %d\n", vv->ov_fb.fmt.bytesperline));
+        }
 
         mutex_unlock(&dev->lock);
         return 0;