On Mon, May 23, 2016 at 05:09:43PM +0300, ville.syrj...@linux.intel.com wrote: > From: Ville Syrjälä <ville.syrj...@linux.intel.com> > > On SNB (at least) it's dangeruopus to hang the GPU with an infinite > batch buffer loop while RPS is disabled. The only thing that keeps > the system going in such circumstances are the internal RPS timers, > so we should never feed the GPU with RPS disabled unless we want to > risk a total system hang. > > Previously we didn't fully disable RPS, but that changes in > commit 2030d684f7b3 ("drm/i915/bxt: Explicitly clear the Turbo control > register") > so we probably didn't see the problem so often previously. But > even before that we were at the mercy of the BIOS for the initial > RPS state, so if the BIOS didn't enable RPS a GPU hang immediately > upon boot could have been fatal. > > To avoid the problems let's just make the RPS enable immediate. > This renders the delayed_resume_work useless actually. We could perhaps > just move the ring freq table initialization to the work and do the > other stull synchronously? > > Fixes: 2030d684f7b3 ("drm/i915/bxt: Explicitly clear the Turbo control > register") > Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com> > --- > This is more and RFC at this point. Perhaps we might want to keep the delayed > work but just for the ring freq table update (which is the main reson this > whole > thing exists in the first place). Another factor is that wait_for() is not > exactly optiomal currently, so it makes the operation slower than it needs to > be. Would need some hard numbers to see if it's worth keeping the delayed work > or not I suppose.
I am in favour - the entire chain should be async, not just this little step to setup the ring freq. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx