[pvrusb2] Re: pvrusb2 driver going into v4l...
isely at isely.net
Wed Nov 9 01:41:07 CST 2005
On Tue, 8 Nov 2005, Frans Meulenbroeks wrote:
> This seems a good way forward, but it is unclear to me
> what we loose/where the incompatibilities are.
The issue I was discussing here only dealt with maintaining backwards
compatibility with older kernels and/or versions of ivtv. For the driver
going into V4L this is less of an issue, but if I try to continue
maintaining that sort of compatibility with more bleeding edge out-of-tree
snapshots, then the code will diverge, something which would complicate
putting this into V4L in the first place.
> I would definitely regret it if this means loosing the
> sys interface (probably with the serial nr) as
> discussed before.
This is a whole different issue. At this point I have no intent of seeing
the sysfs interface go away. I mentioned a while back that this might be
a problem, but right now I am not treating it as such and plan on it being
there along with everything else.
There is a also a debugging interface hiding in sysfs as well. It's only
really documented to the extent that you have to use a piece of that in
order to do the full manual firmware extraction (which almost nobody ever
needs to do). This debug interface includes a simple command interpreter,
and I know this is a type of thing which should not really be going into
the kernel. I've already raised this issue with Mauro; he replied that it
may be able to go in anyway. However I'm working on an idea that will
allow me to keep the debug interface out-of-tree if needed yet possibly
still be loadable as a separate module into the kernel-resident pvrusb2
driver. So I'm not that concerned about this issue.
Actually, I'm thinking about making the debug interface a full fledged
sibling interface right alongside sysfs itself and V4L, and using that
obvious boundary as a module loading shearing layer - then we could have
pvrusb2.ko as the core driver, pvrusb2-sysfs.ko as the sysfs binding,
pvrusb2-v4l.ko as a the V4L binding, pvrusb2-debug.ko as the debug
interface binding, and maybe in the future pvrusb2-dvb.ko as the
hypothetical dvb binding. But that's just a crazy idea bouncing around in
my head right now and I still have to think about it some more...
> If the names in sys change, I don't mind that much.
> For the programming interface: Well, I use the sys
> interface only (being a lazy sod), so I really have no
> opinion here. I'd like to know though, because if that
> changes I definitely do not want to move from the sys
> interface to a programming interface with my proggie
> at this point in time.
I don't have any plans at this point of changing any names in sysfs
related to this driver, beyond *possibly* an impact with the 2 names
related to the debug interface (neither of which I think anyone is using
anyway). So you shouldn't have to worry about anything here.
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