From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mario Kleiner Subject: Re: [Intel-gfx] BUG: sleeping function called from invalid context on 3.10.10-rt7 Date: Thu, 26 Sep 2013 18:16:47 +0200 Message-ID: <52445DEF.1060007@gmail.com> References: <20130911102809.GA31663@uudg.org> <20130911092623.42efd930@gandalf.local.home> <5230895B.5070400@hurleysoftware.com> <20130911113845.6d56a556@gandalf.local.home> <5230C52E.3050801@hurleysoftware.com> <5238B288.3000704@hurleysoftware.com> <523CC728.4040302@tuebingen.mpg.de> <20130923083841.GT4531@intel.com> <5242674A.8020100@tuebingen.mpg.de> <20130925101301.6cbe5d0f@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Mario Kleiner , Peter Hurley , Clark Williams , Daniel Vetter , Sebastian Andrzej Siewior , LKML , "dri-devel@lists.freedesktop.org" , Dave Airlie , Thomas Gleixner , "Luis Claudio R. Goncalves" , intel-gfx , linux-rt-users , =?ISO-8859-1?Q?Ville_Syrj=E4l=E4?= To: Steven Rostedt Return-path: In-Reply-To: <20130925101301.6cbe5d0f@gandalf.local.home> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On 25.09.13 16:13, Steven Rostedt wrote: > On Wed, 25 Sep 2013 06:32:10 +0200 > Mario Kleiner wrote: > > >> But given the new situation, your proposal is great! If we push the >> clock readouts into the get_scanoutpos routine, we can make this robust >> without causing grief for the rt people and without the need for a new >> separate lock for display regs in intel-kms. >> >> E.g., for intel-kms: >> >> i915_get_crtc_scanoutpos(..., ktime_t *stime, ktime_t *etime) >> { >> ... >> spin_lock_irqsave(...uncore.lock); >> preempt_disable(); >> *stime = ktime_get(); >> position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)); >> *etime = ktime_get(); >> preempt_enable(); >> spin_unlock_irqrestore(...uncore.lock) >> ... >> } >> >> With your patchset to reduce the amount of register reads needed in that >> function, and given that forcewake handling isn't needed for these >> registers, this should make it robust again and wouldn't need new locks. >> >> Unless ktime_get is also a bad thing to do in a preempt disabled section? > > ktime_get() works fine in preempt_disable sections, although it may add > some latencies, but you shouldn't need to worry about it. > > I like this solution the best too, but if it does go in, I would ask to > send us the patch for adding the preempt_disable() and we can add the > preempt_disable_rt() to it. Why make mainline have a little more > overhead? > > -- Steve Good! I will do that. Thanks for clarifying the irq and constraints on raw locks in the other thread. -mario > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx >