| Message ID | 1468856499-19246-1-git-send-email-cpaul@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 18, 2016 at 11:41 AM, Lyude <cpaul@redhat.com> wrote: > Just about all of amdgpu's connector probing functions try to acquire > runtime PM refs. If we try to do this in the context of > amdgpu_resume_kms by calling drm_helper_hpd_irq_event(), we end up > deadlocking the system. > > Since we're guaranteed to be holding the spinlock for RPM in > amdgpu_resume_kms, and we already know the GPU is in working order, we > need to prevent the RPM helpers from trying to run during the initial > connector reprobe on resume. > > There's a couple of solutions I've explored for fixing this, but this > one by far seems to be the simplest and most reliable (plus I'm pretty > sure that's what disable_depth is there for anyway). > > Reproduction recipe: > - Get any laptop dual GPUs using PRIME > - Make sure runtime PM is enabled for amdgpu > - Boot the machine > - If the machine managed to boot without hanging, switch out of X to > another VT. This should definitely cause X to hang infinitely. > > Changes since v1: > - add appropriate #ifdef checks for CONFIG_PM. This is not very > useful, but it appears some kernel test suites test compiling amdgpu > with CONFIG_PM disabled, which results in this patch breaking the builds > if we don't include this #ifdef > > Cc: stable@vger.kernel.org > Cc: Alex Deucher <alexdeucher@gmail.com> > Signed-off-by: Lyude <cpaul@redhat.com> Applied. Thanks! Alex > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c > index 6e92008..b7f5650 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c > @@ -1841,7 +1841,23 @@ int amdgpu_resume_kms(struct drm_device *dev, bool resume, bool fbcon) > } > > drm_kms_helper_poll_enable(dev); > + > + /* > + * Most of the connector probing functions try to acquire runtime pm > + * refs to ensure that the GPU is powered on when connector polling is > + * performed. Since we're calling this from a runtime PM callback, > + * trying to acquire rpm refs will cause us to deadlock. > + * > + * Since we're guaranteed to be holding the rpm lock, it's safe to > + * temporarily disable the rpm helpers so this doesn't deadlock us. > + */ > +#ifdef CONFIG_PM > + dev->dev->power.disable_depth++; > +#endif > drm_helper_hpd_irq_event(dev); > +#ifdef CONFIG_PM > + dev->dev->power.disable_depth--; > +#endif > > if (fbcon) { > amdgpu_fbdev_set_suspend(adev, 0); > -- > 2.7.4 >
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 6e92008..b7f5650 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -1841,7 +1841,23 @@ int amdgpu_resume_kms(struct drm_device *dev, bool resume, bool fbcon) } drm_kms_helper_poll_enable(dev); + + /* + * Most of the connector probing functions try to acquire runtime pm + * refs to ensure that the GPU is powered on when connector polling is + * performed. Since we're calling this from a runtime PM callback, + * trying to acquire rpm refs will cause us to deadlock. + * + * Since we're guaranteed to be holding the rpm lock, it's safe to + * temporarily disable the rpm helpers so this doesn't deadlock us. + */ +#ifdef CONFIG_PM + dev->dev->power.disable_depth++; +#endif drm_helper_hpd_irq_event(dev); +#ifdef CONFIG_PM + dev->dev->power.disable_depth--; +#endif if (fbcon) { amdgpu_fbdev_set_suspend(adev, 0);
Just about all of amdgpu's connector probing functions try to acquire runtime PM refs. If we try to do this in the context of amdgpu_resume_kms by calling drm_helper_hpd_irq_event(), we end up deadlocking the system. Since we're guaranteed to be holding the spinlock for RPM in amdgpu_resume_kms, and we already know the GPU is in working order, we need to prevent the RPM helpers from trying to run during the initial connector reprobe on resume. There's a couple of solutions I've explored for fixing this, but this one by far seems to be the simplest and most reliable (plus I'm pretty sure that's what disable_depth is there for anyway). Reproduction recipe: - Get any laptop dual GPUs using PRIME - Make sure runtime PM is enabled for amdgpu - Boot the machine - If the machine managed to boot without hanging, switch out of X to another VT. This should definitely cause X to hang infinitely. Changes since v1: - add appropriate #ifdef checks for CONFIG_PM. This is not very useful, but it appears some kernel test suites test compiling amdgpu with CONFIG_PM disabled, which results in this patch breaking the builds if we don't include this #ifdef Cc: stable@vger.kernel.org Cc: Alex Deucher <alexdeucher@gmail.com> Signed-off-by: Lyude <cpaul@redhat.com> --- drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)