drm/i915: cancel hotplug and dig_port work during suspend and unload

Make sure these work handlers don't run after we system suspend or
unload the driver. Note that we don't cancel the handlers during runtime
suspend. That could lead to a lockup, since we take a runtime PM ref
from the handlers themselves. Fortunaltely canceling there is not needed
since the RPM ref itself provides for the needed serialization.

v2:
- fix the order of canceling dig_port_work wrt. hotplug_work (Ville)
- zero out {long,short}_hpd_port_mask and hpd_event_bits for speed
(Ville)

Signed-off-by: Imre Deak <[e-mail]>
Reviewed-by: Ville Syrjälä <[e-mail]>
Cc: [e-mail] (3.16+)
Signed-off-by: Jani Nikula <[e-mail]>

drivers/gpu/drm/i915/i915_drv.c

···
 	return true;
 }
 
+void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
+{
+	spin_lock_irq(&dev_priv->irq_lock);
+
+	dev_priv->long_hpd_port_mask = 0;
+	dev_priv->short_hpd_port_mask = 0;
+	dev_priv->hpd_event_bits = 0;
+
+	spin_unlock_irq(&dev_priv->irq_lock);
+
+	cancel_work_sync(&dev_priv->dig_port_work);
+	cancel_work_sync(&dev_priv->hotplug_work);
+	cancel_delayed_work_sync(&dev_priv->hotplug_reenable_work);
+}
+
 static int i915_drm_freeze(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
···
 		flush_delayed_work(&dev_priv->rps.delayed_resume_work);
 
 		intel_runtime_pm_disable_interrupts(dev);
+		intel_hpd_cancel_work(dev_priv);
 
 		intel_suspend_gt_powersave(dev);
 

drivers/gpu/drm/i915/i915_drv.h

···
 extern unsigned long i915_gfx_val(struct drm_i915_private *dev_priv);
 extern void i915_update_gfx_val(struct drm_i915_private *dev_priv);
 int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool on);
+void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
 
 extern void intel_console_resume(struct work_struct *work);
 

drivers/gpu/drm/i915/intel_display.c

···
 	 * experience fancy races otherwise.
 	 */
 	drm_irq_uninstall(dev);
-	cancel_work_sync(&dev_priv->hotplug_work);
-	cancel_delayed_work_sync(&dev_priv->hotplug_reenable_work);
+	intel_hpd_cancel_work(dev_priv);
 	dev_priv->pm._irqs_disabled = true;
 
 	/*