drm/i915: Do not clobber config status after a forced restore of hw state

We call intel_modeset_setup_hw_state() along two paths, driver
load/resume and after a lid event notification. During initialisation of
the driver, it is imperative that we reset the config state. This
correctly sets up the initial connector statuses and prepares the
hardware for a thorough probing. However, during a lid event, we only
want to undo the damage caused by the bios by resetting our last known
mode. In this cirumstance, we do not want to clobber our desired state.

In order to try and keep sanity between the config state and our own
tracking, do the drm_mode_config_reset() first along the load/resume
paths before reading out the hw state and apply any definite known
corrections.

v2: "As discussed on irc I don't think we should force the connector
state to anything here: Imo connector->status should reflect what we
believe to be the true output connection state, whereas connector->encoder
reflects whether this connector is wired up to a pipe. And since we no
longer reject modeset on disconnected connectors and never nuked the pipe
if the connector gets disconnected there's no reason for that - such policy
is userspace's job.

This regression has been introduced in

commit 2e938892
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 11 20:08:24 2012 +0200

    drm/i915/crt: explicitly set up HOTPLUG_BITS on resume"
so sayeth Daniel.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org (v3.8 and later)
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -651,6 +651,7 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
 		intel_modeset_init_hw(dev);
 
 		drm_modeset_lock_all(dev);
+		drm_mode_config_reset(dev);
 		intel_modeset_setup_hw_state(dev, true);
 		drm_modeset_unlock_all(dev);
 

drivers/gpu/drm/i915/intel_display.c

@@ -11036,8 +11036,6 @@ void intel_modeset_setup_hw_state(struct drm_device *dev,
 	}
 
 	intel_modeset_check_state(dev);
-
-	drm_mode_config_reset(dev);
 }
 
 void intel_modeset_gem_init(struct drm_device *dev)
@@ -11047,6 +11045,7 @@ void intel_modeset_gem_init(struct drm_device *dev)
 	intel_setup_overlay(dev);
 
 	drm_modeset_lock_all(dev);
+	drm_mode_config_reset(dev);
 	intel_modeset_setup_hw_state(dev, false);
 	drm_modeset_unlock_all(dev);
 }