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

[Mauro Carvalho Chehab <mchehab@kernel.org>]

Em Sat, 11 Sep 2021 10:20:07 -0400
Steven Rostedt <rostedt@goodmis.org> escreveu:

> On Sat, 11 Sep 2021 03:20:50 +0300
> Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:
> 
> > > Freely accessible documentation is really the key.    
> > 
> > In principle I'd agree, but that assumes such documentation would exist
> > in the first place, with a sufficient level of quality. In many cases an
> > open implementation the exercises all device features is a better form
> > of documentation than what vendors have, even internally. Of course, the
> > opposite is true as well, having seen too much vendor code for my own
> > good, there is such a thing as a working for unreadable implementation.
> > 
> > I fully agree with your point about feature completeness by the way,
> > vendors will always find ways to hide pieces of the API if they really
> > want to, but I think that would be true of documentation as well.  
> 
> I would like not only documentation, but also an open source test suite
> that simply tests the interface. Honestly, I believe that all new
> interfaces to the kernel (open or not) should have full documentation
> and a test suite interface before it gets accepted.

Fully agreed.

> We have
> tools/selftests that should be updated with all new interfaces into the
> kernel.
> 
> Even if it's just a smoke test, that would be fine. Obviously if
> there's a driver without hardware, it can't be tested. But if you have
> that hardware, perhaps there could be a simple test suite of the
> interface to let you know it is still functional.

Those days, if a vendor is adding support for a hardware that requires 
a new API, it usually means that it is a new hardware under development.
Only such vendor may have the hardware. A smoke test would mean about
nothing to the ones reviewing the patches, except if the vendor will
also be shipping it to the reviewers.

Thanks,
Mauro