[PATCH 0/5] Fix deadlock on runtime suspend in DRM drivers

[Lukas Wunner]

On Sun, Feb 11, 2018 at 06:58:11PM +0000, Mike Lothian wrote:
> On 11 February 2018 at 09:38, Lukas Wunner <lukas at wunner.de> wrote:
> > The patches for radeon and amdgpu are compile-tested only, I only have a
> > MacBook Pro with an Nvidia GK107 to test.  To test the patches, add an
> > "msleep(12*1000);" at the top of the driver's ->runtime_suspend hook.
> > This ensures that the poll worker runs after ->runtime_suspend has begun.
> > Wait 12 sec after the GPU has begun runtime suspend, then check
> > /sys/bus/pci/devices/0000:01:00.0/power/runtime_status.  Without this
> > series, the status will be stuck at "suspending" and you'll get hung task
> > errors in dmesg after a few minutes.
> 
> I wasn't quite sure where to add that msleep. I've tested the patches
> as is on top of agd5f's wip branch without ill effects
> 
> I've had a radeon and now a amdgpu PRIME setup and don't believe I've
> ever seen this issue
> 
> If you could pop a patch together for the msleep I'll give it a test on
> amdgpu

Here you go, this is for all 3 drivers.
Should deadlock without the series.
Thanks!


diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 50afcf6..eefa0d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -718,6 +718,9 @@ static int amdgpu_pmops_runtime_suspend(struct device *dev)
 		return -EBUSY;
 	}
 
+	printk("waiting 12 sec\n");
+	msleep(12*1000);
+	printk("done waiting 12 sec\n");
 	drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
 	drm_kms_helper_poll_disable(drm_dev);
 	vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_OFF);
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 555fbe5..ee7cf0d 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -586,6 +586,7 @@ static void output_poll_execute(struct work_struct *work)
 		repoll = true;
 		goto out;
 	}
+	dev_info(&dev->pdev->dev, "begin poll\n");
 
 	drm_connector_list_iter_begin(dev, &conn_iter);
 	drm_for_each_connector_iter(connector, &conn_iter) {
@@ -651,6 +652,7 @@ static void output_poll_execute(struct work_struct *work)
 
 	if (repoll)
 		schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
+	dev_info(&dev->pdev->dev, "end poll\n");
 }
 
 /**
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 3e29302..f9da5bc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -855,6 +855,9 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
 		return -EBUSY;
 	}
 
+	printk("waiting 12 sec\n");
+	msleep(12*1000);
+	printk("done waiting 12 sec\n");
 	drm_kms_helper_poll_disable(drm_dev);
 	vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_OFF);
 	nouveau_switcheroo_optimus_dsm();
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 31dd04f..707b8aa 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -413,6 +413,9 @@ static int radeon_pmops_runtime_suspend(struct device *dev)
 		return -EBUSY;
 	}
 
+	printk("waiting 12 sec\n");
+	msleep(12*1000);
+	printk("done waiting 12 sec\n");
 	drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
 	drm_kms_helper_poll_disable(drm_dev);
 	vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_OFF);