linux-kernel - [PATCH 4.4 33/46] drm/nouveau: Dont enabling polling twice on runtime resume

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Date:   Thu, 15 Jun 2017 19:52:52 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lyude <lyude@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Kilian Singer <kilian.singer@...ntumtechnology.info>,
        Lukas Wunner <lukas@...ner.de>,
        David Airlie <airlied@...hat.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 33/46] drm/nouveau: Dont enabling polling twice on runtime resume

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lyude Paul <lyude@...hat.com>


[ Upstream commit cae9ff036eea577856d5b12860b4c79c5e71db4a ]

As it turns out, on cards that actually have CRTCs on them we're already
calling drm_kms_helper_poll_enable(drm_dev) from
nouveau_display_resume() before we call it in
nouveau_pmops_runtime_resume(). This leads us to accidentally trying to
enable polling twice, which results in a potential deadlock between the
RPM locks and drm_dev->mode_config.mutex if we end up trying to enable
polling the second time while output_poll_execute is running and holding
the mode_config lock. As such, make sure we only enable polling in
nouveau_pmops_runtime_resume() if we need to.

This fixes hangs observed on the ThinkPad W541

Signed-off-by: Lyude <lyude@...hat.com>
Cc: Hans de Goede <hdegoede@...hat.com>
Cc: Kilian Singer <kilian.singer@...ntumtechnology.info>
Cc: Lukas Wunner <lukas@...ner.de>
Cc: David Airlie <airlied@...hat.com>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/nouveau/nouveau_display.c |    3 ++-
 drivers/gpu/drm/nouveau/nouveau_drm.c     |    5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -370,7 +370,8 @@ nouveau_display_init(struct drm_device *
 		return ret;
 
 	/* enable polling for external displays */
-	drm_kms_helper_poll_enable(dev);
+	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) {
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -743,7 +743,10 @@ nouveau_pmops_runtime_resume(struct devi
 	pci_set_master(pdev);
 
 	ret = nouveau_do_resume(drm_dev, true);
-	drm_kms_helper_poll_enable(drm_dev);
+
+	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);