RFC: removal of video/radio/vbi_nr module options?

RFC: removal of video/radio/vbi_nr module options?

[Hans Verkuil]

Hi all,

I'm working on cleaning up some old radio drivers and while doing that I
started wondering about the usefulness of the radio_nr module option (and
the corresponding video_nr/vbi_nr module options for video devices).

Is that really still needed? It originates from pre-udev times, but it seems
fairly useless to me these days.

It is also hit-and-miss whether a driver supports it (e.g. uvc doesn't and
nobody seems to miss it) and if it does, whether it is an array (and how
long that array is) or a single integer.

So my question is: when I'm cleaning up drivers like the old radio drivers,
should I keep support for those module options or should I just drop it?

I'm curious what people think.

Regards,

	Hans

Re: RFC: removal of video/radio/vbi_nr module options?

[Devin Heitmueller]

On Fri, Jan 27, 2012 at 2:21 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> Hi all,
>
> I'm working on cleaning up some old radio drivers and while doing that I
> started wondering about the usefulness of the radio_nr module option (and
> the corresponding video_nr/vbi_nr module options for video devices).
>
> Is that really still needed? It originates from pre-udev times, but it seems
> fairly useless to me these days.

I can tell you from lurking in the mythtv-users IRC channel, that
there are still many, many users of video_nr.  Yes, they can in theory
accomplish the same thing through udev, but they aren't today, and if
you remove the functionality you'll have lots of users scambling to
figure out why stuff that previously worked is now broken.  This tends
to be more an issue with tuner cards than uvc devices, presumably
because MythTV starts up unattended and you're more likely to have
more than one capture device.

My hope is that once the media controller interface becomes more
mature (including adoption by userland applications such as Myth) that
it will eliminate the need for these sorts of hacks entirely.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

Re: RFC: removal of video/radio/vbi_nr module options?

[Mauro Carvalho Chehab]

Em 27-01-2012 11:36, Devin Heitmueller escreveu:
> On Fri, Jan 27, 2012 at 2:21 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
>> Hi all,
>>
>> I'm working on cleaning up some old radio drivers and while doing that I
>> started wondering about the usefulness of the radio_nr module option (and
>> the corresponding video_nr/vbi_nr module options for video devices).
>>
>> Is that really still needed? It originates from pre-udev times, but it seems
>> fairly useless to me these days.
> 
> I can tell you from lurking in the mythtv-users IRC channel, that
> there are still many, many users of video_nr.  Yes, they can in theory
> accomplish the same thing through udev, but they aren't today, and if
> you remove the functionality you'll have lots of users scambling to
> figure out why stuff that previously worked is now broken.  This tends
> to be more an issue with tuner cards than uvc devices, presumably
> because MythTV starts up unattended and you're more likely to have
> more than one capture device.

This were never needed by USB devices. In general, due to USB bandwidth
constraints, users can't plug more than one or a few devices on a USB bus.

MythTV is not the only usercase for it. Surveillance system can have
multiple devices in the same PCI card, and it is not uncommon to find
hardware with multiple PCI multi-input cards. Several of those boards
don't even have eeprom.

Regards,
Mauro