V4L/DVB (6392): bttv: Update initial image size when set via V4L1 VIDIOCMCAPTURE
authorTrent Piepho <xyzzy@speakeasy.org>
Mon, 22 Oct 2007 20:44:55 +0000 (17:44 -0300)
committerMauro Carvalho Chehab <mchehab@infradead.org>
Sun, 4 Nov 2007 23:41:16 +0000 (21:41 -0200)
commita8ab68bffe3fe7b8e9ff963ea321d283fc77ac5f
treecc0b0d7e19baf0df9b92cbf6093ae5cc9ad83256
parent35378434e739ac869d0146a47133a0f9d6fd2ee8
V4L/DVB (6392): bttv: Update initial image size when set via V4L1 VIDIOCMCAPTURE

The V4L1 spec says that the image size should be with with VIDIOCSWIN before
requesting buffers with VIDIOCGMBUF and capturing into them with
VIDIOCMCAPTURE.

But it seems that many apps don't do this.  They set the size using the fields
in the VIDIOCMCAPTURE ioctl.  The driver doesn't know what size to capture
until it actually starts to capture.  In particular, it doesn't know what size
to capture until it has already mmap the captured buffers.  Which is quite
stupid.  Why V4L1 has size and format fields for VIDIOCMCAPTURE I have no idea.

Many drivers don't support this, including those using v4l1-compat.

The bttv does, which is probably the only reason such broken software is so
prevalent.

But, the driver doesn't adjust its idea of what size is being captured when it
is set this way.  If you try to query the driver's current setting with
v4l2-ctl, it won't be correct.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
drivers/media/video/bt8xx/bttv-driver.c