Linux v4.7

drm-amdgpu-Disable-RPM-helpers-while-reprobing.patch

@@ -0,0 +1,70 @@
+From patchwork Fri Jul  8 15:37:35 2016
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: drm/amdgpu: Disable RPM helpers while reprobing connectors on resume
+From: cpaul@redhat.com
+X-Patchwork-Id: 97837
+Message-Id: <1467992256-23832-1-git-send-email-cpaul@redhat.com>
+To: amd-gfx@lists.freedesktop.org
+Cc: Tom St Denis <tom.stdenis@amd.com>, Jammy Zhou <Jammy.Zhou@amd.com>,
+ open list <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
+ "open list:RADEON and AMDGPU DRM DRIVERS"
+ <dri-devel@lists.freedesktop.org>, 
+ Alex Deucher <alexander.deucher@amd.com>, Lyude <cpaul@redhat.com>,
+ Flora Cui <Flora.Cui@amd.com>,
+ =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
+ Monk Liu <Monk.Liu@amd.com>
+Date: Fri,  8 Jul 2016 11:37:35 -0400
+
+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>
+---
+ 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);