drm/i915: Unlock panel even when LVDS is disabled

commit b0616c53 upstream.

Otherwise we'll have backtraces in assert_panel_unlocked because the
BIOS locks the register. In the reporter's case this regression was
introduced in

commit c31407a3
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Oct 18 21:07:01 2012 +0100

    drm/i915: Add no-lvds quirk for Supermicro X7SPA-H
Reported-by: Alexey Orishko <alexey.orishko@gmail.com>
Cc: Alexey Orishko <alexey.orishko@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Francois Tigeot <ftigeot@wolfpond.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Tested-by: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/i915/intel_lvds.c

@@ -893,6 +893,17 @@ void intel_lvds_init(struct drm_device *dev)
 	int pipe;
 	u8 pin;
 
+	/*
+	 * Unlock registers and just leave them unlocked. Do this before
+	 * checking quirk lists to avoid bogus WARNINGs.
+	 */
+	if (HAS_PCH_SPLIT(dev)) {
+		I915_WRITE(PCH_PP_CONTROL,
+			   I915_READ(PCH_PP_CONTROL) | PANEL_UNLOCK_REGS);
+	} else {
+		I915_WRITE(PP_CONTROL,
+			   I915_READ(PP_CONTROL) | PANEL_UNLOCK_REGS);
+	}
 	if (!intel_lvds_supported(dev))
 		return;
 
@@ -1088,17 +1099,6 @@ void intel_lvds_init(struct drm_device *dev)
 	DRM_DEBUG_KMS("detected %s-link lvds configuration\n",
 		      lvds_encoder->is_dual_link ? "dual" : "single");
 
-	/*
-	 * Unlock registers and just
-	 * leave them unlocked
-	 */
-	if (HAS_PCH_SPLIT(dev)) {
-		I915_WRITE(PCH_PP_CONTROL,
-			   I915_READ(PCH_PP_CONTROL) | PANEL_UNLOCK_REGS);
-	} else {
-		I915_WRITE(PP_CONTROL,
-			   I915_READ(PP_CONTROL) | PANEL_UNLOCK_REGS);
-	}
 	lvds_connector->lid_notifier.notifier_call = intel_lid_notify;
 	if (acpi_lid_notifier_register(&lvds_connector->lid_notifier)) {
 		DRM_DEBUG_KMS("lid notifier registration failed\n");