drm/i915: Move compute part of __intel_set_mode() to separate function

The first function calls done in that function can still cause changes
to the atomic state and may fail. This should eventually be part of our
atomic check function, while the rest of the code in __intel_set_mode()
is the commit hook. So this makes the legacy mode set more atomic-y.
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -12232,6 +12232,32 @@ static int __intel_set_mode_setup_plls(struct drm_atomic_state *state)
 	return ret;
 }
 
+/* Code that should eventually be part of atomic_check() */
+static int __intel_set_mode_checks(struct drm_atomic_state *state)
+{
+	struct drm_device *dev = state->dev;
+	int ret;
+
+	/*
+	 * See if the config requires any additional preparation, e.g.
+	 * to adjust global state with pipes off.  We need to do this
+	 * here so we can get the modeset_pipe updated config for the new
+	 * mode set on this crtc.  For other crtcs we need to use the
+	 * adjusted_mode bits in the crtc directly.
+	 */
+	if (IS_VALLEYVIEW(dev) || IS_BROXTON(dev)) {
+		ret = valleyview_modeset_global_pipes(state);
+		if (ret)
+			return ret;
+	}
+
+	ret = __intel_set_mode_setup_plls(state);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int __intel_set_mode(struct drm_crtc *modeset_crtc,
 			    struct drm_display_mode *mode,
 			    int x, int y, struct drm_framebuffer *fb,
@@ -12247,29 +12273,16 @@ static int __intel_set_mode(struct drm_crtc *modeset_crtc,
 	int ret = 0;
 	int i;
 
+	ret = __intel_set_mode_checks(state);
+	if (ret < 0)
+		return ret;
+
 	crtc_state_copy = kmalloc(sizeof(*crtc_state_copy), GFP_KERNEL);
 	if (!crtc_state_copy) {
 		ret = -ENOMEM;
 		goto done;
 	}
 
-	/*
-	 * See if the config requires any additional preparation, e.g.
-	 * to adjust global state with pipes off.  We need to do this
-	 * here so we can get the modeset_pipe updated config for the new
-	 * mode set on this crtc.  For other crtcs we need to use the
-	 * adjusted_mode bits in the crtc directly.
-	 */
-	if (IS_VALLEYVIEW(dev) || IS_BROXTON(dev)) {
-		ret = valleyview_modeset_global_pipes(state);
-		if (ret)
-			goto done;
-	}
-
-	ret = __intel_set_mode_setup_plls(state);
-	if (ret)
-		goto done;
-
 	for_each_crtc_in_state(state, crtc, crtc_state, i) {
 		if (!needs_modeset(crtc_state))
 			continue;