On Tuesday 24 March 2009 00:14:07 Alexey Klimov wrote:
> Hello, all
>
> After last convertion of radio drivers to use v4l2_device we have such
> code in many radio drivers:
> (it's radio-terratec.c for example)
>
> ...
> static int terratec_open(struct file *file)
> {
> return 0;
> }
>
> static int terratec_release(struct file *file)
> {
> return 0;
> }
> ...
>
> and
>
> ...
> static int vidioc_g_input(struct file *filp, void *priv, unsigned int
> *i)
> {
> *i = 0;
> return 0;
> }
>
> static int vidioc_s_input(struct file *filp, void *priv, unsigned int i)
> {
> return i ? -EINVAL : 0;
> }
> ...
>
> Such code used in many radio-drivers as i understand.
>
> Is it good to place this empty and almost empty functions in:
> (here i see two variants)
>
> 1) In header file that be in linux/drivers/media/radio/ directory.
> Later, we can move some generic/or repeating code in this header.
>
> 2) In any v4l header. What header may contain this ?
>
> ?
>
> For what ? Well, as i understand we can decrease amount of lines and
> provide this simple generic functions. It's like
> video_device_release_empty function behaviour. Maybe not only radio
> drivers can use such vidioc_g_input and vidioc_s_input.
>
> Is it worth ?
I don't think it is worth doing this for g/s_input. I think it is useful to
have them here: it makes it very clear that there is just a single input
and the overhead in both lines and actual bytes is minimal.
But for the empty open and release functions you could easily handle that in
v4l2-dev.c: if you leave the open and release callbacks to NULL, then
v4l2_open and v4l2_release can just return 0. That would be nice.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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