drm: Stop updating plane->crtc/fb/old_fb on atomic drivers

Stop playing around with plane->crtc/fb/old_fb with atomic
drivers. Make life a lot simpler when we don't have to do the
magic old_fb vs. fb dance around plane updates. That way we
can't risk plane->fb getting out of sync with plane->state->fb
and we're less likely to leak any refcounts as well.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180525185045.29689-14-ville.syrjala@linux.intel.com
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

drivers/gpu/drm/drm_atomic.c

@@ -692,6 +692,11 @@ drm_atomic_get_plane_state(struct drm_atomic_state *state,
 
 	WARN_ON(!state->acquire_ctx);
 
+	/* the legacy pointers should never be set */
+	WARN_ON(plane->fb);
+	WARN_ON(plane->old_fb);
+	WARN_ON(plane->crtc);
+
 	plane_state = drm_atomic_get_existing_plane_state(state, plane);
 	if (plane_state)
 		return plane_state;
@@ -2039,45 +2044,6 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
 	return ret;
 }
 
-/**
- * drm_atomic_clean_old_fb -- Unset old_fb pointers and set plane->fb pointers.
- *
- * @dev: drm device to check.
- * @plane_mask: plane mask for planes that were updated.
- * @ret: return value, can be -EDEADLK for a retry.
- *
- * Before doing an update &drm_plane.old_fb is set to &drm_plane.fb, but before
- * dropping the locks old_fb needs to be set to NULL and plane->fb updated. This
- * is a common operation for each atomic update, so this call is split off as a
- * helper.
- */
-void drm_atomic_clean_old_fb(struct drm_device *dev,
-			     unsigned plane_mask,
-			     int ret)
-{
-	struct drm_plane *plane;
-
-	/* if succeeded, fixup legacy plane crtc/fb ptrs before dropping
-	 * locks (ie. while it is still safe to deref plane->state).  We
-	 * need to do this here because the driver entry points cannot
-	 * distinguish between legacy and atomic ioctls.
-	 */
-	drm_for_each_plane_mask(plane, dev, plane_mask) {
-		if (ret == 0) {
-			struct drm_framebuffer *new_fb = plane->state->fb;
-			if (new_fb)
-				drm_framebuffer_get(new_fb);
-			plane->fb = new_fb;
-			plane->crtc = plane->state->crtc;
-
-			if (plane->old_fb)
-				drm_framebuffer_put(plane->old_fb);
-		}
-		plane->old_fb = NULL;
-	}
-}
-EXPORT_SYMBOL(drm_atomic_clean_old_fb);
-
 /**
  * DOC: explicit fencing properties
  *
@@ -2298,9 +2264,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	unsigned int copied_objs, copied_props;
 	struct drm_atomic_state *state;
 	struct drm_modeset_acquire_ctx ctx;
-	struct drm_plane *plane;
 	struct drm_out_fence_state *fence_state;
-	unsigned plane_mask;
 	int ret = 0;
 	unsigned int i, j, num_fences;
 
@@ -2340,7 +2304,6 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);
 
 retry:
-	plane_mask = 0;
 	copied_objs = 0;
 	copied_props = 0;
 	fence_state = NULL;
@@ -2411,12 +2374,6 @@ retry:
 			copied_props++;
 		}
 
-		if (obj->type == DRM_MODE_OBJECT_PLANE && count_props &&
-		    !(arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)) {
-			plane = obj_to_plane(obj);
-			plane_mask |= (1 << drm_plane_index(plane));
-			plane->old_fb = plane->fb;
-		}
 		drm_mode_object_put(obj);
 	}
 
@@ -2437,8 +2394,6 @@ retry:
 	}
 
 out:
-	drm_atomic_clean_old_fb(dev, plane_mask, ret);
-
 	complete_crtc_signaling(dev, state, fence_state, num_fences, !ret);
 
 	if (ret == -EDEADLK) {

drivers/gpu/drm/drm_atomic_helper.c

@@ -2914,7 +2914,6 @@ static int __drm_atomic_helper_disable_all(struct drm_device *dev,
 	struct drm_plane *plane;
 	struct drm_crtc_state *crtc_state;
 	struct drm_crtc *crtc;
-	unsigned plane_mask = 0;
 	int ret, i;
 
 	state = drm_atomic_state_alloc(dev);
@@ -2957,17 +2956,10 @@ static int __drm_atomic_helper_disable_all(struct drm_device *dev,
 			goto free;
 
 		drm_atomic_set_fb_for_plane(plane_state, NULL);
-
-		if (clean_old_fbs) {
-			plane->old_fb = plane->fb;
-			plane_mask |= BIT(drm_plane_index(plane));
-		}
 	}
 
 	ret = drm_atomic_commit(state);
 free:
-	if (plane_mask)
-		drm_atomic_clean_old_fb(dev, plane_mask, ret);
 	drm_atomic_state_put(state);
 	return ret;
 }
@@ -3129,13 +3121,8 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
 
 	state->acquire_ctx = ctx;
 
-	for_each_new_plane_in_state(state, plane, new_plane_state, i) {
-		WARN_ON(plane->crtc != new_plane_state->crtc);
-		WARN_ON(plane->fb != new_plane_state->fb);
-		WARN_ON(plane->old_fb);
-
+	for_each_new_plane_in_state(state, plane, new_plane_state, i)
 		state->planes[i].old_state = plane->state;
-	}
 
 	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i)
 		state->crtcs[i].old_state = crtc->state;

drivers/gpu/drm/drm_crtc.c

@@ -479,8 +479,12 @@ static int __drm_mode_set_config_internal(struct drm_mode_set *set,
 
 	ret = crtc->funcs->set_config(set, ctx);
 	if (ret == 0) {
-		crtc->primary->crtc = fb ? crtc : NULL;
-		crtc->primary->fb = fb;
+		struct drm_plane *plane = crtc->primary;
+
+		if (!plane->state) {
+			plane->crtc = fb ? crtc : NULL;
+			plane->fb = fb;
+		}
 	}
 
 	drm_for_each_crtc(tmp, crtc->dev) {

drivers/gpu/drm/drm_fb_helper.c

@@ -368,7 +368,6 @@ static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool activ
 	struct drm_plane *plane;
 	struct drm_atomic_state *state;
 	int i, ret;
-	unsigned int plane_mask;
 	struct drm_modeset_acquire_ctx ctx;
 
 	drm_modeset_acquire_init(&ctx, 0);
@@ -381,7 +380,6 @@ static int restore_fbdev_mode_atomic(struct drm_fb_helper *fb_helper, bool activ
 
 	state->acquire_ctx = &ctx;
 retry:
-	plane_mask = 0;
 	drm_for_each_plane(plane, dev) {
 		plane_state = drm_atomic_get_plane_state(state, plane);
 		if (IS_ERR(plane_state)) {
@@ -391,9 +389,6 @@ retry:
 
 		plane_state->rotation = DRM_MODE_ROTATE_0;
 
-		plane->old_fb = plane->fb;
-		plane_mask |= 1 << drm_plane_index(plane);
-
 		/* disable non-primary: */
 		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
 			continue;
@@ -430,8 +425,6 @@ retry:
 	ret = drm_atomic_commit(state);
 
 out_state:
-	drm_atomic_clean_old_fb(dev, plane_mask, ret);
-
 	if (ret == -EDEADLK)
 		goto backoff;
 

drivers/gpu/drm/drm_framebuffer.c

@@ -836,8 +836,6 @@ retry:
 			goto unlock;
 
 		plane_mask |= BIT(drm_plane_index(plane));
-
-		plane->old_fb = plane->fb;
 	}
 
 	/* This list is only filled when disable_crtcs is set. */
@@ -852,9 +850,6 @@ retry:
 		ret = drm_atomic_commit(state);
 
 unlock:
-	if (plane_mask)
-		drm_atomic_clean_old_fb(dev, plane_mask, ret);
-
 	if (ret == -EDEADLK) {
 		drm_atomic_state_clear(state);
 		drm_modeset_backoff(&ctx);

drivers/gpu/drm/drm_plane.c

@@ -651,9 +651,11 @@ static int __setplane_internal(struct drm_plane *plane,
 					 crtc_x, crtc_y, crtc_w, crtc_h,
 					 src_x, src_y, src_w, src_h, ctx);
 	if (!ret) {
-		plane->crtc = crtc;
-		plane->fb = fb;
-		drm_framebuffer_get(plane->fb);
+		if (!plane->state) {
+			plane->crtc = crtc;
+			plane->fb = fb;
+			drm_framebuffer_get(plane->fb);
+		}
 	} else {
 		plane->old_fb = NULL;
 	}
@@ -1093,8 +1095,10 @@ retry:
 		/* Keep the old fb, don't unref it. */
 		plane->old_fb = NULL;
 	} else {
-		plane->fb = fb;
-		drm_framebuffer_get(fb);
+		if (!plane->state) {
+			plane->fb = fb;
+			drm_framebuffer_get(fb);
+		}
 	}
 
 out:

drivers/gpu/drm/drm_plane_helper.c

@@ -502,6 +502,7 @@ EXPORT_SYMBOL(drm_plane_helper_update);
 int drm_plane_helper_disable(struct drm_plane *plane)
 {
 	struct drm_plane_state *plane_state;
+	struct drm_framebuffer *old_fb;
 
 	/* crtc helpers love to call disable functions for already disabled hw
 	 * functions. So cope with that. */
@@ -521,8 +522,9 @@ int drm_plane_helper_disable(struct drm_plane *plane)
 	plane_state->plane = plane;
 
 	plane_state->crtc = NULL;
+	old_fb = plane_state->fb;
 	drm_atomic_set_fb_for_plane(plane_state, NULL);
 
-	return drm_plane_helper_commit(plane, plane_state, plane->fb);
+	return drm_plane_helper_commit(plane, plane_state, old_fb);
 }
 EXPORT_SYMBOL(drm_plane_helper_disable);

include/drm/drm_atomic.h

@@ -601,9 +601,6 @@ int __must_check
 drm_atomic_add_affected_planes(struct drm_atomic_state *state,
 			       struct drm_crtc *crtc);
 
-void
-drm_atomic_clean_old_fb(struct drm_device *dev, unsigned plane_mask, int ret);
-
 int __must_check drm_atomic_check_only(struct drm_atomic_state *state);
 int __must_check drm_atomic_commit(struct drm_atomic_state *state);
 int __must_check drm_atomic_nonblocking_commit(struct drm_atomic_state *state);