Re: [PATCH v4 02/38] drm/i915: Explicit power enable during deferred context initialisation

Chris Wilson
2016-01-12T11:28:35Z

On Tue, Jan 12, 2016 at 11:11:20AM +0000, John Harrison wrote:
> On 12/01/2016 00:20, Chris Wilson wrote:
> >On Mon, Jan 11, 2016 at 06:42:31PM +0000, John.C.Harrison@Intel.com wrote:
> >>From: John Harrison <John.C.Harrison@Intel.com>
> >>
> >>A later patch in this series re-organises the batch buffer submission
> >>code. Part of that is to reduce the scope of a pm_get/put pair.
> >>Specifically, they previously wrapped the entire submission path from
> >>the very start to the very end, now they only wrap the actual hardware
> >>submission part in the back half.
> >However, as you haven't fixed the ordering issue that requires rpm_get
> >before struct_mutex, this is broken.
> Why does 'intel_runtime_pm_get' require the struct mutex to be held?
> It has certainly not complained at me about trying to do stuff
> without it.

Because it depends upon the struct_mutex and rpm doesn't have sufficient
lockdep integration to be able to warn about using rpm from the
incorrect contexts.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre