i915: fix intel graphics suspend breakage due to resume/lid event confusion

In commit c1c7af6089 ("drm/i915: force
mode set at lid open time") the intel graphics driver was taught to
restore the LVDS mode on lid open.

That caused problems with interaction with the suspend/resume code,
which commonly runs at the same time (suspend is often caused by the lid
close event, while lid open is commonly a resume event), which was
worked around with in commit 06891e27a9
("drm/i915: fix suspend/resume breakage in lid notifier").

However, in the meantime the lid event code had also grown a user event
notifier (commit 06324194eee97a51b5f172270df49ec39192d6cc: "drm/i915:
generate a KMS uevent at lid open/close time"), and now _that_ causes
problems with suspend/resume and some versions of Xorg reacting to those
uevents by setting the mode.

So this effectively reverts that commit 06324194ee, and makes the lid
open protection logic against suspend/resume more explicit.  This fixes
at least one laptop. See

	http://bugzilla.kernel.org/show_bug.cgi?id=14484

for more details.

Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_drv.c

@@ -89,7 +89,8 @@ static int i915_suspend(struct drm_device *dev, pm_message_t state)
 		pci_set_power_state(dev->pdev, PCI_D3hot);
 	}
 
-	dev_priv->suspended = 1;
+	/* Modeset on resume, not lid events */
+	dev_priv->modeset_on_lid = 0;
 
 	return 0;
 }
@@ -124,7 +125,7 @@ static int i915_resume(struct drm_device *dev)
 		drm_helper_resume_force_mode(dev);
 	}
 
-	dev_priv->suspended = 0;
+	dev_priv->modeset_on_lid = 0;
 
 	return ret;
 }

drivers/gpu/drm/i915/i915_drv.h

@@ -274,7 +274,7 @@ typedef struct drm_i915_private {
 	struct drm_i915_display_funcs display;
 
 	/* Register state */
-	bool suspended;
+	bool modeset_on_lid;
 	u8 saveLBB;
 	u32 saveDSPACNTR;
 	u32 saveDSPBCNTR;

drivers/gpu/drm/i915/intel_lvds.c

@@ -656,6 +656,15 @@ static int intel_lvds_get_modes(struct drm_connector *connector)
 	return 0;
 }
 
+/*
+ * Lid events. Note the use of 'modeset_on_lid':
+ *  - we set it on lid close, and reset it on open
+ *  - we use it as a "only once" bit (ie we ignore
+ *    duplicate events where it was already properly
+ *    set/reset)
+ *  - the suspend/resume paths will also set it to
+ *    zero, since they restore the mode ("lid open").
+ */
 static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
 			    void *unused)
 {
@@ -663,13 +672,19 @@ static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
 		container_of(nb, struct drm_i915_private, lid_notifier);
 	struct drm_device *dev = dev_priv->dev;
 
-	if (acpi_lid_open() && !dev_priv->suspended) {
+	if (!acpi_lid_open()) {
+		dev_priv->modeset_on_lid = 1;
+		return NOTIFY_OK;
+	}
+
+	if (!dev_priv->modeset_on_lid)
+		return NOTIFY_OK;
+
+	dev_priv->modeset_on_lid = 0;
+
 	mutex_lock(&dev->mode_config.mutex);
 	drm_helper_resume_force_mode(dev);
 	mutex_unlock(&dev->mode_config.mutex);
-	}
-
-	drm_sysfs_hotplug_event(dev_priv->dev);
 
 	return NOTIFY_OK;
 }