> On Tuesday 24 March 2009 08:06:39 Hans Verkuil wrote:
>> 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.
>
> What about making that the default NULL g_input/s_input callbacks handling
> in
> video_ioctl2 ? Devices with a single input wouldn't need to define
> g_input/s_input callbacks at all.
If you leave s/g_input NULL then you have a device without an input at
all. That's perfectly valid for output-only devices.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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