Re: V4L2 dma-buf support test with UVC + i915 test application

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Thursday 08 November 2012 19:14:18 Laurent Pinchart wrote:
> Hi Mauro,
> 
> Here's the application I've used to test V4L2 dma-buf support with a UVC
> webcam and an Intel GPU supported by the i915 driver.
> 
> The kernel code is available in my git tree at
> 
> git://linuxtv.org/pinchartl/media.git devel/dma-buf-v10
> 
> (http://git.linuxtv.org/pinchartl/media.git/shortlog/refs/heads/devel/v4l2-
> clock)
> 
> Don't forget to enable dma-buf and UVC support when compiling the kernel.
> 
> The userspace code is based on the v4l2-drm-example application written by
> Tomasz (the original code is available at
> git://git.infradead.org/users/kmpark/public-apps). I need to clean up my
> modifications to push them back to the repository, in the meantime the code
> is attached to this e-mail.
> 
> To compile the application, just run make with the KDIR variable set to the
> path to your Linux kernel tree with the dma-buf patches applied. Don't
> forget to make headers_install in the kernel tree as the Makefile will look
> for headers in $KDIR/usr.
> 
> You will need a recent version of libdrm with plane support available.
> 2.4.39 should do.
> 
> The following command line will capture VGA YUYV data from the webcam and
> display it on the screen. You need to run it in a console as root without
> the X server running.
> 
> ./dmabuf-sharing -M i915 -o 7:3:1600x900 -i /dev/video0 -S 640,480 -f YUYV
> -F YUYV -s 640,480@0,0 -t 640,480@0,0 -b 2

I forgot to mention that the -o parameter takes the connector ID, CRTC ID and 
mode as parameters. The mode is easy to find, but the connector and CRTC IDs 
are a bit more tricky. You can run the modetest application (part of libdrm 
but not installed by most distributions, so a manual compilation is needed) to 
dump all CRTC, encoder and connector information to the console. Pick the 
connector associated with your display, and the CRTC associated with the 
encoder associated with that connector.

-- 
Regards,

Laurent Pinchart