Hi Daniel,
On 27/04/2021 02:17, Daniel Almeida wrote:
> Hi Hans, Ezequiel & all.
>
> I find it a bit hard to debug my own code when it invariably sneaks in a
> bad control value with the VIDIOC_S_EXT_CTRLS ioctl.
>
>
> I feel that it would be tremendously beneficial to encourage the use of
> dprintk calls in v4l2-ctrls.c to inform the user about what pieces of
> data were actually rejected in the validation functions.
Makes sense!
>
> #define dprintk(vdev, fmt, arg...) do { \
> if (!WARN_ON(!(vdev)) && ((vdev)->dev_debug & V4L2_DEV_DEBUG_CTRL)) \
> printk(KERN_DEBUG pr_fmt("%s: %s: " fmt), \
> __func__, video_device_node_name(vdev), ##arg);
>
>
> Unfortunately the dprintk macro above takes a pointer to struct
> video_device as argument. This is not available in the places I want to
> actually place the calls, as far as I could tell.
>
> E.g. here:
>
> static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
> union v4l2_ctrl_ptr ptr)
>
> I'd like to make the changes to make this possible, if any, or be
> pointed at another solution if there is one - such as calling pr_err
> directly or something along these lines - please.
I have no problem with changing the prototypes to pass a vdev pointer
along. The validate_new function is the starting point for that.
However, keep in mind that it can also be called from a driver via e.g.
__v4l2_ctrl_s_ctrl(), in which case there is no video_device, so the
debug code has to be able to handle the case where vdev == NULL, and
not do a WARN_ON in that case.
I would postpone working on this though. Early in the next cycle I want
to merge a large refactor patch found here:
https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=ctrl-refactor
where v4l2-ctrls.c is split up in several pieces. I suggest you wait until
that's merged before making patches for the control framework.
Regards,
Hans
>
> Kindly advise?
>
> -- thanks
> -- Daniel
>
