Re: [MAINTAINER SUMMIT] User-space requirements for accelerator drivers

Mauro Carvalho Chehab
2021-09-11T22:33:57Z

Em Sat, 11 Sep 2021 12:27:37 +0300
Laurent Pinchart <laurent.pinchart@ideasonboard.com> escreveu:

> Hi Mauro,

> > > > On media, enforcing userspace to always be open source would
> > > > have been very bad, as it would prevent several videoconferencing
> > > > software to exist on Linux.
> > >
> > > Could you elaborate on which software you're thinking of ? And maybe
> > > which driver(s) you're thinking about ?
> >
> > I'm referring to tools like v4l2-compliance, qv4l2 and other tools
> > we maintain at v4l-utils tree.
>
> I meant the video conferencing software that would have been prevented
> from existing. I'd like to understand if you think that requiring *one*
> open userspace would be problematic.

No, requiring *one* open userspace real application should be enough.

> > Yeah, a public datasheet sounds an interesting requirement. It offers
> > a problem, though: maybe some details could be missed on it, which
> > would prevent any real open source userspace development.
>
> Absolutely, and I don't think we can come up with any process and
> technical measure that would prevent a vendor from cheating if they
> really want to. It will always be possible to hide some features behind
> reserved registers that wouldn't need to be programmed for basic
> operation but that would be crucial to optimize the quality or
> performances. This is regardless of whether we want to enforce openness
> of documentation in the form of datasheets or source code.

Unfortunately true.

> I'm not too concerned about this though. If we can address most of this
> issue with a clear process and message I think it would be a very good
> step forward already.

Yeah, a policy could be implemented in order to address such cases,
asking the vendor for a fix or even removing drivers and banning
vendors that are, by purpose, sending broken drivers/APIs.

Thanks,
Mauro