[Intel-gfx] [PATCH 05/10] drm/i915: Add debugfs interface for Displayport debug and compliance testing

[Jesse Barnes]

On Fri, 14 Nov 2014 07:00:17 +1000
Dave Airlie <airlied at gmail.com> wrote:

> > Aside from all this (and now with my community hat on) just adding
> > code to get a sticker (labelled "passed DP validation") which is
> > separate code and not used by actual users is imo not useful for
> > merging upstream. But that's just my own opinion, not sure what's
> > Dave's stance here or whether there's much precendence either way.
> >
> > So short answer: I still think exposing this with properties is the
> > right approach, presuming we really need it (and it's not just to
> > paper over a deficient link training logic in the kernel). I also
> > think it'll be less code since we can simplify the debugfs option
> > parser.  
> 
> Don't expose DP stuff in properties, I don't want users controlling
> the parameters of the DP link in any way. I can't see any use
> in userspace for controlling this stuff. So I'm happier with debugfs,
> to avoid making an ABI we hate later.
> 
> Yes I do prefer we make DP validation go via the same paths,
> but some parts of DP validation require things userspace shouldn't
> be allowed setup, and for those we should have bypasses, everything
> else should be done via normal channels.

Yeah, agreed on re-using code paths.  I just don't think it means we
have to re-use ioctl or property entry points.  The internals of the
debugfs file can just as easily call internal functions as the
ioctl/property code, so I think we can be covered that way too.

I guess we'll have to check out Todd's latest patches when he posts
them.

Jesse