Re: [PATCH] drm/i915: Revert "drm/i915: Reject the pin ioctl on gen6+"

[Damien Lespiau <damien.lespiau@intel.com>]

Hi Daniel,

On Mon, Jul 07, 2014 at 11:04:55PM +0200, Daniel Vetter wrote:
> On Thu, Jul 03, 2014 at 08:12:35AM +0100, Damien Lespiau wrote:
> > This reverts commit 02f6bcccf7c324115747aae2f0addd6af5d321cd.
> > 
> > The OA buffer can contain global data (in particular, not linked to a
> > context or a single batch execution) about GPU events (eg. hw context
> > switches, rc6 transitions, frequency changes, ...) and needs to be
> > mapped to GGTT. The pin ioctl provided a way to do that.
> > 
> > Admittedly, this change broke what seems to be a valid use case of
> > pinning a buffer in GGTT, even when PPGTT is used (which is the reason
> > invoked in the commit message).
> 
> Global OA buffers should be handled by the kernel and exposed through
> perf, imo. I think I'll go lalala on this a bit longer ...

Do you think that we can unblock this now that we have somewhat of path
forward with Rob Bragg's work? I'm still uneasy with a precedent where
we break working applications and it takes a long time for us to revert
the offending change?

Thanks!

-- 
Damien