[PATCH v9 06/11] drm/i915: Enable i915 perf stream for Haswell OA unit

[sourab gupta]

On Mon, 2016-11-07 at 11:49 -0800, Robert Bragg wrote:
> Gen graphics hardware can be set up to periodically write snapshots of
> performance counters into a circular buffer via its Observation
> Architecture and this patch exposes that capability to userspace via
> the
> i915 perf interface.
> 
> v2:
>    Make sure to initialize ->specific_ctx_id when opening, without
>    relying on _pin_notify hook, in case ctx already pinned.
> v3:
>    Revert back to pinning ctx upfront when opening stream, removing
>    need to hook in to pinning and to update OACONTROL on the fly.
> 
> Signed-off-by: Robert Bragg <robert at sixbynine.org>
> Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>
Have been working for quite some time on extending the interfaces per
the usecase of multiple concurrent streams (on different engines), and
infrastructure fits quite well for these usecases. With Chris' comments
addressed, the patch can have my r-b.
Reviewed-by: Sourab Gupta <sourab.gupta at intel.com>