drm/gem-vram: Share code between GEM VRAM's _{prepare, cleanup}_fb()

The error-recovery code in drm_gem_vram_plane_helper_prepare_fb() is of
the same pattern as drm_gem_vram_plane_helper_cleanup_fb(). Implement
both of them using an internal helper. No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220517113327.26919-4-tzimmermann@suse.de

drivers/gpu/drm/drm_gem_vram_helper.c

@@ -9,6 +9,7 @@
 #include <drm/drm_file.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_gem_ttm_helper.h>
 #include <drm/drm_gem_vram_helper.h>
 #include <drm/drm_managed.h>
@@ -630,6 +631,24 @@ EXPORT_SYMBOL(drm_gem_vram_driver_dumb_create);
  * Helpers for struct drm_plane_helper_funcs
  */
 
+static void __drm_gem_vram_plane_helper_cleanup_fb(struct drm_plane *plane,
+						   struct drm_plane_state *state,
+						   unsigned int num_planes)
+{
+	struct drm_gem_object *obj;
+	struct drm_gem_vram_object *gbo;
+	struct drm_framebuffer *fb = state->fb;
+
+	while (num_planes) {
+		--num_planes;
+		obj = drm_gem_fb_get_obj(fb, num_planes);
+		if (!obj)
+			continue;
+		gbo = drm_gem_vram_of_gem(obj);
+		drm_gem_vram_unpin(gbo);
+	}
+}
+
 /**
  * drm_gem_vram_plane_helper_prepare_fb() - \
  *	Implements &struct drm_plane_helper_funcs.prepare_fb
@@ -671,11 +690,7 @@ drm_gem_vram_plane_helper_prepare_fb(struct drm_plane *plane,
 	return 0;
 
 err_drm_gem_vram_unpin:
-	while (i) {
-		--i;
-		gbo = drm_gem_vram_of_gem(new_state->fb->obj[i]);
-		drm_gem_vram_unpin(gbo);
-	}
+	__drm_gem_vram_plane_helper_cleanup_fb(plane, new_state, i);
 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_vram_plane_helper_prepare_fb);
@@ -694,18 +709,12 @@ void
 drm_gem_vram_plane_helper_cleanup_fb(struct drm_plane *plane,
 				     struct drm_plane_state *old_state)
 {
-	size_t i;
-	struct drm_gem_vram_object *gbo;
+	struct drm_framebuffer *fb = old_state->fb;
 
-	if (!old_state->fb)
+	if (!fb)
 		return;
 
-	for (i = 0; i < ARRAY_SIZE(old_state->fb->obj); ++i) {
-		if (!old_state->fb->obj[i])
-			continue;
-		gbo = drm_gem_vram_of_gem(old_state->fb->obj[i]);
-		drm_gem_vram_unpin(gbo);
-	}
+	__drm_gem_vram_plane_helper_cleanup_fb(plane, old_state, ARRAY_SIZE(fb->obj));
 }
 EXPORT_SYMBOL(drm_gem_vram_plane_helper_cleanup_fb);