Re: [PATCH] drm/i915: remove user GTT mappings early during runtime suspend

[Imre Deak <imre.deak@intel.com>]

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On Tue, 2014-05-06 at 12:40 +0100, Chris Wilson wrote:
> On Tue, May 06, 2014 at 02:28:50PM +0300, Imre Deak wrote:
> > Currently user space can access GEM buffers mapped to GTT through
> > existing mappings concurrently while the platform specific suspend
> > handlers are running.  Since these handlers may change the HW state in a
> > way that would break such accesses, remove the mappings before calling
> > the handlers.
> 
> Hmm, but you never locked the device, so what is preventing those
> concurrent accesses from refaulting in GTT entires anyway. Please explain
> the context under which the runtime suspend code executes, and leave
> that explanation within easy reach of intel_runtime_suspend() -
> preferrably with testing of those assumptions.

During faulting we take an RPM reference, so that avoids concurrent
re-faults. I could add a comment about this to the code.

--Imre


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