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

Daniel Vetter daniel at ffwll.ch
Wed Jan 4 19:12:57 CET 2012

On Wed, Jan 04, 2012 at 09:54:08AM -0800, Keith Packard wrote:
> 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.

The "Correct?" was just to check my understanding of your concern, I still
think its invalid. You've cut away the second part of my mail where I
explain why and I don't see you responding to that here. Also
micro-optimizing the gpu reset code sounds a bit strange.
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48

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