Re: v4l2 kernel module debugging methods

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

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Le dimanche 06 décembre 2015 à 00:00 +0200, Ran Shalit a écrit :
> Hello,
> 
> I would like to ask a general question regarding methods to debug a
> v4l2 device driver.
> Since I assume that the kernel driver will probably won't work in
> first try after coding everything inside the device driver...
> 
> 1. Do you think qemu/kgdb debugger is a good method for the device
> driver debugging , or is it plain printing ?
> 
> 2. Is there a simple way to display the image of a YUV-like buffer in
> memory ?

Most Linux distribution ships GStreamer. You can with GStreamer read
and display a raw YUV images (you need to know the specific format)
using videoparse element.

  gst-launch-1.0 filesrc location=my.yuv ! videoparse format=yuy2 width=320 height=240 ! imagefreeze ! videoconvert ! autovideosink

You could also encode and store to various formats, replacing the
imagefreeze ... section with an encoder and a filesink. Note that
videoparse unfortunatly does not allow passing strides array or
offsets. So it will work only if you set the width/height to padded
width/height.

regards,
Nicolas

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