Patch "drm/nouveau: Fix drm poll_helper handling" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

drm/nouveau: Fix drm poll_helper handling

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-nouveau-fix-drm-poll_helper-handling.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Ujfalusi <[email protected]>
Date: Mon, 15 May 2017 12:04:31 +0300
Subject: drm/nouveau: Fix drm poll_helper handling

From: Peter Ujfalusi <[email protected]>

[ Upstream commit 9a2eba337cacefc95b97c2726e3efdd435b3460e ]

Commit cae9ff036eea effectively disabled the drm poll_helper by checking the wrong flag to see if the driver should enable the poll or not:
mode_config.poll_enabled is only set to true by poll_init and it is not indicating if the poll is enabled or not. nouveau_display_create() will initialize the poll and going to disable it right away. After poll_init() the mode_config.poll_enabled will be true, but the poll itself is disabled.

To avoid the race caused by calling the poll_enable() from different paths, this patch will enable the poll from one place, in the nouveau_display_hpd_work().

In case the pm_runtime is disabled we will enable the poll in nouveau_drm_load() once.

---
 drivers/gpu/drm/nouveau/nouveau_display.c |    6 ++----
 drivers/gpu/drm/nouveau/nouveau_drm.c     |    6 +++---
 2 files changed, 5 insertions(+), 7 deletions(-)

@@ -367,6 +367,8 @@ nouveau_display_hpd_work(struct work_str
 	pm_runtime_get_sync(drm->dev->dev);
 
 	drm_helper_hpd_irq_event(drm->dev);
+	/* enable polling for external displays */
+	drm_kms_helper_poll_enable(drm->dev);
 
 	pm_runtime_mark_last_busy(drm->dev->dev);
 	pm_runtime_put_sync(drm->dev->dev);

@@ -420,10 +422,6 @@ nouveau_display_init(struct drm_device *
 	if (ret)
 		return ret;
 
-	/* enable polling for external displays */
-	if (!dev->mode_config.poll_enabled)
-		drm_kms_helper_poll_enable(dev);
-
 	/* enable hotplug interrupts */
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 		struct nouveau_connector *conn = nouveau_connector(connector);

@@ -483,6 +483,9 @@ nouveau_drm_load(struct drm_device *dev,
 		pm_runtime_allow(dev->dev);
 		pm_runtime_mark_last_busy(dev->dev);
 		pm_runtime_put(dev->dev);
+	} else {
+		/* enable polling for external displays */
+		drm_kms_helper_poll_enable(dev);
 	}
 	return 0;
 

@@ -762,9 +765,6 @@ nouveau_pmops_runtime_resume(struct devi
 
 	ret = nouveau_do_resume(drm_dev, true);
 
-	if (!drm_dev->mode_config.poll_enabled)
-		drm_kms_helper_poll_enable(drm_dev);
-
 	/* do magic */
 	nvif_mask(&device->object, 0x088488, (1 << 25), (1 << 25));
 	vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_ON);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/drm-nouveau-fix-drm-poll_helper-handling.patch