On Fri, Jul 8, 2016 at 11:37 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.
Cc: stable@vger.kernel.org Signed-off-by: Lyude cpaul@redhat.com
Applied. thanks!
Alex
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 6e92008..46c1fee 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -1841,7 +1841,19 @@ 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.*/dev->dev->power.disable_depth++; drm_helper_hpd_irq_event(dev);dev->dev->power.disable_depth--; if (fbcon) { amdgpu_fbdev_set_suspend(adev, 0);-- 2.7.4
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