drm/i915: always preserve bios swizzling

Currently we only set preserve_bios_swizzling when the initial fb is
shared and totally miss the single-screen case. Fix this by
consolidating all the logic for both cases.

This seems to go back to when swizzle preservation was originally
merged in

commit d9ceb8163339134bd3ffb9fb87a0db4698283e32
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Thu Oct 9 12:57:43 2014 -0700

    drm/i915: preserve swizzle settings if necessary v4

Cc: Kristian Høgsberg <hoegsberg@gmail.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -2543,14 +2543,11 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
 	mode_cmd.flags = DRM_MODE_FB_MODIFIERS;
 
 	mutex_lock(&dev->struct_mutex);
-
 	if (intel_framebuffer_init(dev, to_intel_framebuffer(fb),
 				   &mode_cmd, obj)) {
 		DRM_DEBUG_KMS("intel fb init failed\n");
 		goto out_unref_obj;
 	}
-
-	obj->frontbuffer_bits = INTEL_FRONTBUFFER_PRIMARY(crtc->pipe);
 	mutex_unlock(&dev->struct_mutex);
 
 	DRM_DEBUG_KMS("initial plane fb obj %p\n", obj);
@@ -2585,19 +2582,15 @@ intel_find_initial_plane_obj(struct intel_crtc *intel_crtc,
 	struct drm_crtc *c;
 	struct intel_crtc *i;
 	struct drm_i915_gem_object *obj;
+	struct drm_plane *primary = intel_crtc->base.primary;
+	struct drm_framebuffer *fb;
 
 	if (!plane_config->fb)
 		return;
 
 	if (intel_alloc_initial_plane_obj(intel_crtc, plane_config)) {
-		struct drm_plane *primary = intel_crtc->base.primary;
-
-		primary->fb = &plane_config->fb->base;
-		primary->state->crtc = &intel_crtc->base;
-		primary->crtc = &intel_crtc->base;
-		update_state_fb(primary);
-
-		return;
+		fb = &plane_config->fb->base;
+		goto valid_fb;
 	}
 
 	kfree(plane_config->fb);
@@ -2615,25 +2608,29 @@ intel_find_initial_plane_obj(struct intel_crtc *intel_crtc,
 		if (!i->active)
 			continue;
 
-		obj = intel_fb_obj(c->primary->fb);
-		if (obj == NULL)
+		fb = c->primary->fb;
+		if (!fb)
 			continue;
 
+		obj = intel_fb_obj(fb);
 		if (i915_gem_obj_ggtt_offset(obj) == plane_config->base) {
-			struct drm_plane *primary = intel_crtc->base.primary;
-
-			if (obj->tiling_mode != I915_TILING_NONE)
-				dev_priv->preserve_bios_swizzle = true;
-
-			drm_framebuffer_reference(c->primary->fb);
-			primary->fb = c->primary->fb;
-			primary->state->crtc = &intel_crtc->base;
-			primary->crtc = &intel_crtc->base;
-			update_state_fb(intel_crtc->base.primary);
-			obj->frontbuffer_bits |= INTEL_FRONTBUFFER_PRIMARY(intel_crtc->pipe);
-			break;
+			drm_framebuffer_reference(fb);
+			goto valid_fb;
 		}
 	}
+
+	return;
+
+valid_fb:
+	obj = intel_fb_obj(fb);
+	if (obj->tiling_mode != I915_TILING_NONE)
+		dev_priv->preserve_bios_swizzle = true;
+
+	primary->fb = fb;
+	primary->state->crtc = &intel_crtc->base;
+	primary->crtc = &intel_crtc->base;
+	update_state_fb(primary);
+	obj->frontbuffer_bits |= INTEL_FRONTBUFFER_PRIMARY(intel_crtc->pipe);
 }
 
 static void i9xx_update_primary_plane(struct drm_crtc *crtc,