From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933070Ab0FQQlA (ORCPT ); Thu, 17 Jun 2010 12:41:00 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:43239 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756615Ab0FQQk7 convert rfc822-to-8bit (ORCPT ); Thu, 17 Jun 2010 12:40:59 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=TyOaspmzme0cUu4IWGSAEw0Nq/DrJeyZvo2OomooJMslOmIi95WeutIVhRRlSLB3or D2B0+64ahSfAdBnh0yKDh8CebfCRbpEgjU7k9nsQuodUV8vVwfR9L5xm8TX+YT2XBwUh /qi8a6Fra9h1SGyk9yQ5lbLQbquVvFGcqioz8= MIME-Version: 1.0 In-Reply-To: <201006171821.37060.rjw@sisk.pl> References: <201006141653.03879.rjw@sisk.pl> <201006162216.49756.rjw@sisk.pl> <201006171821.37060.rjw@sisk.pl> Date: Thu, 17 Jun 2010 12:40:57 -0400 Message-ID: Subject: Re: [Regression, post-2.6.34] Hibernation broken on machines with radeon/KMS and r300 From: Alex Deucher To: "Rafael J. Wysocki" Cc: Ondrej Zary , Dave Airlie , Linus Torvalds , Andrew Morton , linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dri-devel Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2010/6/17 Rafael J. Wysocki : > On Wednesday, June 16, 2010, Alex Deucher wrote: >> On Wed, Jun 16, 2010 at 4:16 PM, Rafael J. Wysocki wrote: >> > On Wednesday, June 16, 2010, Ondrej Zary wrote: >> >> On Wednesday 16 June 2010, Rafael J. Wysocki wrote: >> >> > On Tuesday, June 15, 2010, Rafael J. Wysocki wrote: >> >> > > On Monday, June 14, 2010, Alex Deucher wrote: >> >> > > > On Mon, Jun 14, 2010 at 3:03 PM, Rafael J. Wysocki wrote: >> >> > > > > On Monday, June 14, 2010, Alex Deucher wrote: >> >> > > > >> On Mon, Jun 14, 2010 at 10:53 AM, Rafael J. Wysocki >> >> wrote: >> >> > > > >> > Alex, Dave, >> >> > > > >> > >> >> > > > >> > I'm afraid hibernation is broken on all machines using radeon/KMS >> >> > > > >> > with r300 after commit ce8f53709bf440100cb9d31b1303291551cf517f >> >> > > > >> > (drm/radeon/kms/pm: rework power management).  At least, I'm able >> >> > > > >> > to reproduce the symptom, which is that the machine hangs hard >> >> > > > >> > around the point where an image is created (probably during the >> >> > > > >> > device thaw phase), on two different boxes with r300 (the output >> >> > > > >> > of lspci from one of them is attached for reference, the other one >> >> > > > >> > is HP nx6325). >> >> > > > >> > >> >> > > > >> > Suspend to RAM appears to work fine at least on one of the >> >> > > > >> > affected boxes. >> >> > > > >> > >> >> > > > >> > Unfortunately, the commit above changes a lot of code and it's not >> >> > > > >> > too easy to figure out what's wrong with it and I didn't have the >> >> > > > >> > time to look more into details of this failure.  However, it looks >> >> > > > >> > like you use .suspend() and .resume() callbacks as .freeze() and >> >> > > > >> > .thaw() which may not be 100% correct (in fact it looks like the >> >> > > > >> > "legacy" PCI suspend/resume is used, which is not recommended any >> >> > > > >> > more). >> >> > > > >> >> >> > > > >> Does it work any better after Dave's last drm pull request? >> >> > > > > >> >> > > > > Nope.  The symptom is slightly different, though, because now it >> >> > > > > hangs after turning off the screen. >> >> > > > > >> >> > > > >> With the latest changes, pm should not be a factor unless it's >> >> > > > >> explicitly enabled via sysfs. >> >> > > > > >> >> > > > > Well, I guess the first pm patch changed more than just pm, then. >> >> > > > >> >> > > > Does this patch help? >> >> > > > http://lists.freedesktop.org/archives/dri-devel/2010-June/001314.html >> >> > > >> >> > > No, it doesn't.  I try to hibernate, everything works to the point where >> >> > > the screen goes off and the box hangs (solid).  Normally, it would turn >> >> > > the screen back on and continue with saving the image. >> >> > > >> >> > > But, since that happens with the patch above applied, I think it doesn't >> >> > > really pass the suspend phase (IOW, it probably hangs somewhere in the >> >> > > radeon's suspend routine). >> >> > >> >> > I've just verified that in fact hibernation works on HP nx6325 with >> >> > 2.6.35-rc3, but it takes about 55 sec. to suspend the graphics adapter in >> >> > the "freeze" phase.  Surprisingly enough, during suspend to RAM it works >> >> > normally (as well as in the "poweroff" phase of hibernation). >> >> >> >> It takes 2 minutes on RV530: >> >> https://bugzilla.redhat.com/show_bug.cgi?id=586522 >> > >> > Well, my second affected box appears to hang somewhere in the radeon's suspend >> > routine. >> >> Does the attached patch help? > > It helps, but from what I can see in the code, it still has a few problems. > > First, the mutex around cancel_delayed_work() in radeon_pm_suspend() > doesn't really serve any purpose, because rdev->pm.pm_method cannot change > at this point and cancel_delayed_work() only tries to delete the work's timer. > Moreover, it doesn't prevent the work handler from running, in which case the > handler can do some wrong things and will rearm itself to do some more wrong > things going forward.  So, I think it's better to wait for the handler to run in case it's > already been queued up and it should also be prevented from rearming itself in > that case. > > Second, in radeon_set_pm_method() the cancel_delayed_work() is not sufficient > to prevent the work handler from running and queing up itself for the next run > (the failure scenario is that cancel_delayed_work_sync() returns 0, so the > handler is run, it waits on the mutex and then rearms itself after the mutex > has been released), so it looks like cancel_delayed_work_sync() > should be used to make sure it's not going to run again, but calling > that cancel_delayed_work_sync() from under the mutex is not a good idea. > > Finally, there's a potential deadlock in radeon_pm_fini(), where > cancel_delayed_work_sync() is called under rdev->pm.mutex, but the > work handler tries to acquire the same mutex (if it wins the race). > > So, I think something like the appended patch is needed. > Looks reasonable. Does it fix the suspend issue? Alex > Rafael > > > Signed-off-by: Rafael J. Wysocki > --- >  drivers/gpu/drm/radeon/radeon.h    |    3 +- >  drivers/gpu/drm/radeon/radeon_pm.c |   41 ++++++++++++++++++++++++++++++------- >  2 files changed, 36 insertions(+), 8 deletions(-) > > Index: linux-2.6/drivers/gpu/drm/radeon/radeon_pm.c > =================================================================== > --- linux-2.6.orig/drivers/gpu/drm/radeon/radeon_pm.c > +++ linux-2.6/drivers/gpu/drm/radeon/radeon_pm.c > @@ -397,13 +397,20 @@ static ssize_t radeon_set_pm_method(stru >                rdev->pm.dynpm_planned_action = DYNPM_ACTION_DEFAULT; >                mutex_unlock(&rdev->pm.mutex); >        } else if (strncmp("profile", buf, strlen("profile")) == 0) { > +               bool flush_wq = false; > + >                mutex_lock(&rdev->pm.mutex); > -               rdev->pm.pm_method = PM_METHOD_PROFILE; > +               if (rdev->pm.pm_method == PM_METHOD_DYNPM) { > +                       cancel_delayed_work(&rdev->pm.dynpm_idle_work); > +                       flush_wq = true; > +               } >                /* disable dynpm */ >                rdev->pm.dynpm_state = DYNPM_STATE_DISABLED; >                rdev->pm.dynpm_planned_action = DYNPM_ACTION_NONE; > -               cancel_delayed_work(&rdev->pm.dynpm_idle_work); > +               rdev->pm.pm_method = PM_METHOD_PROFILE; >                mutex_unlock(&rdev->pm.mutex); > +               if (flush_wq) > +                       flush_workqueue(rdev->wq); >        } else { >                DRM_ERROR("invalid power method!\n"); >                goto fail; > @@ -418,9 +425,18 @@ static DEVICE_ATTR(power_method, S_IRUGO > >  void radeon_pm_suspend(struct radeon_device *rdev) >  { > +       bool flush_wq = false; > + >        mutex_lock(&rdev->pm.mutex); > -       cancel_delayed_work(&rdev->pm.dynpm_idle_work); > +       if (rdev->pm.pm_method == PM_METHOD_DYNPM) { > +               cancel_delayed_work(&rdev->pm.dynpm_idle_work); > +               if (rdev->pm.dynpm_state == DYNPM_STATE_ACTIVE) > +                       rdev->pm.dynpm_state = DYNPM_STATE_SUSPENDED; > +               flush_wq = true; > +       } >        mutex_unlock(&rdev->pm.mutex); > +       if (flush_wq) > +               flush_workqueue(rdev->wq); >  } > >  void radeon_pm_resume(struct radeon_device *rdev) > @@ -432,6 +448,12 @@ void radeon_pm_resume(struct radeon_devi >        rdev->pm.current_sclk = rdev->clock.default_sclk; >        rdev->pm.current_mclk = rdev->clock.default_mclk; >        rdev->pm.current_vddc = rdev->pm.power_state[rdev->pm.default_power_state_index].clock_info[0].voltage.voltage; > +       if (rdev->pm.pm_method == PM_METHOD_DYNPM > +           && rdev->pm.dynpm_state == DYNPM_STATE_SUSPENDED) { > +               rdev->pm.dynpm_state = DYNPM_STATE_ACTIVE; > +               queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work, > +                                       msecs_to_jiffies(RADEON_IDLE_LOOP_MS)); > +       } >        mutex_unlock(&rdev->pm.mutex); >        radeon_pm_compute_clocks(rdev); >  } > @@ -486,6 +508,8 @@ int radeon_pm_init(struct radeon_device >  void radeon_pm_fini(struct radeon_device *rdev) >  { >        if (rdev->pm.num_power_states > 1) { > +               bool flush_wq = false; > + >                mutex_lock(&rdev->pm.mutex); >                if (rdev->pm.pm_method == PM_METHOD_PROFILE) { >                        rdev->pm.profile = PM_PROFILE_DEFAULT; > @@ -493,13 +517,16 @@ void radeon_pm_fini(struct radeon_device >                        radeon_pm_set_clocks(rdev); >                } else if (rdev->pm.pm_method == PM_METHOD_DYNPM) { >                        /* cancel work */ > -                       cancel_delayed_work_sync(&rdev->pm.dynpm_idle_work); > +                       cancel_delayed_work(&rdev->pm.dynpm_idle_work); > +                       flush_wq = true; >                        /* reset default clocks */ >                        rdev->pm.dynpm_state = DYNPM_STATE_DISABLED; >                        rdev->pm.dynpm_planned_action = DYNPM_ACTION_DEFAULT; >                        radeon_pm_set_clocks(rdev); >                } >                mutex_unlock(&rdev->pm.mutex); > +               if (flush_wq) > +                       flush_workqueue(rdev->wq); > >                device_remove_file(rdev->dev, &dev_attr_power_profile); >                device_remove_file(rdev->dev, &dev_attr_power_method); > @@ -720,12 +747,12 @@ static void radeon_dynpm_idle_work_handl >                        radeon_pm_get_dynpm_state(rdev); >                        radeon_pm_set_clocks(rdev); >                } > + > +               queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work, > +                                       msecs_to_jiffies(RADEON_IDLE_LOOP_MS)); >        } >        mutex_unlock(&rdev->pm.mutex); >        ttm_bo_unlock_delayed_workqueue(&rdev->mman.bdev, resched); > - > -       queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work, > -                                       msecs_to_jiffies(RADEON_IDLE_LOOP_MS)); >  } > >  /* > Index: linux-2.6/drivers/gpu/drm/radeon/radeon.h > =================================================================== > --- linux-2.6.orig/drivers/gpu/drm/radeon/radeon.h > +++ linux-2.6/drivers/gpu/drm/radeon/radeon.h > @@ -619,7 +619,8 @@ enum radeon_dynpm_state { >        DYNPM_STATE_DISABLED, >        DYNPM_STATE_MINIMUM, >        DYNPM_STATE_PAUSED, > -       DYNPM_STATE_ACTIVE > +       DYNPM_STATE_ACTIVE, > +       DYNPM_STATE_SUSPENDED, >  }; >  enum radeon_dynpm_action { >        DYNPM_ACTION_NONE, >