Hi Philipp,
On Tuesday 10 November 2009 17:13:18 Philipp Wiesner wrote:
> I'm having some trouble using gstreamer with soc_camera and am a
> modified tw9910 driver. I had difficulties compiling the latest sources
> for my target so I'm using old kernel and gstreamer versions. But my
> question may still be valid, because the problem doesn't seem to be fixed
> and this may be interesting for driver programming in the future.
>
> The part I'm suspecting is
>
> if (v4l2_ioctl (fd, VIDIOC_S_FMT, &format) < 0) {
> if (errno != EINVAL)
> goto set_fmt_failed;
>
> [v4l2src_calls.c,1223]
> According to V4L2 api documentation drivers should set errno, but all
> drivers I've seen in the soc_camera framework (including soc_camera.c)
> only 'return -errno'. Should device drivers (like tw9910) set errno or
> should soc_camera use return values and set errno? Is it correct that none
> of them happens at the moment?
errno is a userspace variable. Kernel drivers return a negative error code
which is stored into errno by the ioctl() function in glibc.
--
Regards,
Laurent Pinchart
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