[Intel-gfx] [PATCH 06/43] drm/i915: protect force_wake_(get|put) with the gt_lock

[Keith Packard]

On Wed, 4 Jan 2012 18:11:18 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:

> Ah, I think I see you're concern: Between the time we reset the gpu
> and the time we fix up the forcewake state somebody might sneak in and
> see an inconstency between our tracking and the actual hw state, hence
> reading garbage. Correct?

Indeed. Plus, holding the spinlock across the whole operation also means
only taking it once, rather than twice. Spinlocks aren't free.

If we change the locking from struct_mutex to the spinlock, we should
actually make it work, independent of what access we have today.

-- 
keith.packard at intel.com
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