[PATCH] drm/i915: enable irqs earlier when resuming

[Daniel Vetter <daniel.vetter@ffwll.ch>]

We need it to restore the ilk rc6 context, since the gpu wait no
requires interrupts. But in general having interrupts around should
help in code sanity, since more and more stuff is interrupt driven.

This regression has been introduced in

commit 3e9605018ab3e333d51cc90fccfde2031886763b
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Nov 27 16:22:54 2012 +0000

    drm/i915: Rearrange code to only have a single method for waiting upon the ring

Like in the driver load code we need to make sure that hotplug
interrupts don't cause havoc with our modeset state, hence block them
with the existing infrastructure. Again we ignore races where we might
loose hotplug interrupts ...

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=54691
Cc: stable@vger.kernel.org (for 3.8 only)
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reported-and-Tested-by: Ilya Tumaykin <itumaykin@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_drv.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b342749..7589a2a 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -493,6 +493,7 @@ static int i915_drm_freeze(struct drm_device *dev)
 		intel_modeset_disable(dev);
 
 		drm_irq_uninstall(dev);
+		dev_priv->enable_hotplug_processing = false;
 	}
 
 	i915_save_state(dev);
@@ -566,10 +567,20 @@ static int __i915_drm_thaw(struct drm_device *dev)
 		error = i915_gem_init_hw(dev);
 		mutex_unlock(&dev->struct_mutex);
 
+		/* We need working interrupts for modeset enabling ... */
+		drm_irq_install(dev);
+
 		intel_modeset_init_hw(dev);
 		intel_modeset_setup_hw_state(dev, false);
-		drm_irq_install(dev);
+
+		/*
+		 * ... but also need to make sure that hotplug processing
+		 * doesn't cause havoc. Like in the driver load code we don't
+		 * bother with the tiny race here where we might loose hotplug
+		 * notifications.
+		 * */
 		intel_hpd_init(dev);
+		dev_priv->enable_hotplug_processing = true;
 	}
 
 	intel_opregion_init(dev);
-- 
1.7.10.4