drm/atomic: Create __drm_atomic_helper_crtc_reset() for subclassing crtc_state.

We already have __drm_atomic_helper_connector_reset() and
__drm_atomic_helper_plane_reset(), extend this to crtc as well.

This will allow us to set default values in the crtc_state, without
having to do it in each driver separately.

Of all drivers that need conversion, only nouveau is done in this
commit, because it wrote its own __drm_atomic_helper_crtc_reset(),
clashing with the drm core.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190301125627.7285-3-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/drm_atomic_state_helper.c

@@ -56,6 +56,29 @@
  * for these functions.
  */
 
+/**
+ * __drm_atomic_helper_crtc_reset - reset state on CRTC
+ * @crtc: drm CRTC
+ * @crtc_state: CRTC state to assign
+ *
+ * Initializes the newly allocated @crtc_state and assigns it to
+ * the &drm_crtc->state pointer of @crtc, usually required when
+ * initializing the drivers or when called from the &drm_crtc_funcs.reset
+ * hook.
+ *
+ * This is useful for drivers that subclass the CRTC state.
+ */
+void
+__drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
+			       struct drm_crtc_state *crtc_state)
+{
+	if (crtc_state)
+		crtc_state->crtc = crtc;
+
+	crtc->state = crtc_state;
+}
+EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset);
+
 /**
  * drm_atomic_helper_crtc_reset - default &drm_crtc_funcs.reset hook for CRTCs
  * @crtc: drm CRTC
@@ -65,14 +88,13 @@
  */
 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
 {
-	if (crtc->state)
-		__drm_atomic_helper_crtc_destroy_state(crtc->state);
-
-	kfree(crtc->state);
-	crtc->state = kzalloc(sizeof(*crtc->state), GFP_KERNEL);
+	struct drm_crtc_state *crtc_state =
+		kzalloc(sizeof(*crtc->state), GFP_KERNEL);
 
 	if (crtc->state)
-		crtc->state->crtc = crtc;
+		crtc->funcs->atomic_destroy_state(crtc, crtc->state);
+
+	__drm_atomic_helper_crtc_reset(crtc, crtc_state);
 }
 EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);
 

drivers/gpu/drm/nouveau/dispnv50/head.c

@@ -419,16 +419,6 @@ nv50_head_atomic_duplicate_state(struct drm_crtc *crtc)
 	return &asyh->state;
 }
 
-static void
-__drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
-			       struct drm_crtc_state *state)
-{
-	if (crtc->state)
-		crtc->funcs->atomic_destroy_state(crtc, crtc->state);
-	crtc->state = state;
-	crtc->state->crtc = crtc;
-}
-
 static void
 nv50_head_reset(struct drm_crtc *crtc)
 {
@@ -437,6 +427,9 @@ nv50_head_reset(struct drm_crtc *crtc)
 	if (WARN_ON(!(asyh = kzalloc(sizeof(*asyh), GFP_KERNEL))))
 		return;
 
+	if (crtc->state)
+		nv50_head_atomic_destroy_state(crtc, crtc->state);
+
 	__drm_atomic_helper_crtc_reset(crtc, &asyh->state);
 }
 

include/drm/drm_atomic_state_helper.h

@@ -37,6 +37,8 @@ struct drm_private_state;
 struct drm_modeset_acquire_ctx;
 struct drm_device;
 
+void __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
+				    struct drm_crtc_state *state);
 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc);
 void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
 					      struct drm_crtc_state *state);