From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: paper over missed irq issues with force wake vodoo Date: Wed, 11 Jan 2012 10:59:20 +0100 Message-ID: <20120111095920.GA3855@phenom.ffwll.local> References: <1325702445-2231-1-git-send-email-daniel.vetter@ffwll.ch> <20120110122006.GD3979@phenom.ffwll.local> <87fwfnnjsz.fsf@eliezer.anholt.net> <861ur6alwb.fsf@sumi.keithp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ww0-f43.google.com (mail-ww0-f43.google.com [74.125.82.43]) by gabe.freedesktop.org (Postfix) with ESMTP id B435B9F588 for ; Wed, 11 Jan 2012 01:58:25 -0800 (PST) Received: by wgbdt11 with SMTP id dt11so495672wgb.12 for ; Wed, 11 Jan 2012 01:58:24 -0800 (PST) Content-Disposition: inline In-Reply-To: <861ur6alwb.fsf@sumi.keithp.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Keith Packard Cc: Daniel Vetter , intel-gfx , Eugeni Dodonov , stable@kernel.org List-Id: intel-gfx@lists.freedesktop.org On Tue, Jan 10, 2012 at 08:44:20PM -0800, Keith Packard wrote: > On Tue, 10 Jan 2012 16:51:08 -0800, Eric Anholt wrote: > > > So they've gone out of their way to build broken stuff. Awesome. > > Well, in theory, the interrupt would be generated *before* the hardware > goes to RC6; when idle, I'm not exactly sure what the hardware would be > doing to generate interrupts. I agree, we still have no explanation for why the hw seems to forget to push out the irq/seqno write before going into sleep (and then seems to drop the irq right on the floor). I suspect that the windows driver just grabs frocewake every time it's interested in an interrupt and hence this irq/seqno signalling part without forcewake wasn't ever properly validated. After all there must be a reason for the multi-threaded forcewake stuff on windows - on Linux (before the voodoo patch at least) we don't use forcewake at all in any fastpath ... Unfortunately round-trip times with vpg are a disaster and we're not allowed to look at the windows kernel driver code to check ourselves :( I need to again work on getting some access to it. > > I'd say you've found the clue here -- I'm a lot happier with going with > > your patches now (and I was pretty happy with the gen7 side before). > > I'd just like to not mess with gen6 unless we've got missed irq bugs > > there to fix. > > Yeah, knowing that there might be interrupt funnies due to RC6 goes some > way to explaining why just avoiding RC6 helps. > > I wonder if any of this might explain the RC6 issues we see on SNB on > some hardware, and whether we should give this a try... I know, grasping > at straws, but still, it's about all we have at this point. I'm already playing around with patches that grab forcewake a bit more to work out a magic trick for semaphores vs. vt-d. Utter fail atm, everything I try seems to blow up faster :( So we still have an elephant somewhere. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48