drm: Resurrect atomic rmfb code, v3

This was somehow lost between v3 and the merged version in Maarten's
patch merged as:

commit f2d580b9
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Wed May 4 14:38:26 2016 +0200

    drm/core: Do not preserve framebuffer on rmfb, v4.

This introduces a slight behavioral change to rmfb. Instead of
disabling a crtc when the primary plane is disabled, we try to
preserve it.

Apart from old versions of the vmwgfx xorg driver, there is
nothing depending on rmfb disabling a crtc. Since vmwgfx is
a legacy driver we can safely only disable the plane with atomic.

If this commit is rejected by the driver then we will still fall
back to the old behavior and turn off the crtc.

v2:
- Remove plane->fb assignment, done by drm_atomic_clean_old_fb.
- Add WARN_ON when atomic_remove_fb fails.
- Always call drm_atomic_state_put.
v3:
- Use drm_drv_uses_atomic_modeset
- Handle the case where the first plane-disable-only commit fails
  with -EINVAL. Some drivers do not support this, fall back to
  disabling all crtc's in this case.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/66fc3da5-697b-1613-0a67-a5293209f0dc@linux.intel.com

drivers/gpu/drm/drm_atomic.c

@@ -2046,6 +2046,112 @@ static void complete_crtc_signaling(struct drm_device *dev,
 	kfree(fence_state);
 }
 
+int drm_atomic_remove_fb(struct drm_framebuffer *fb)
+{
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_device *dev = fb->dev;
+	struct drm_atomic_state *state;
+	struct drm_plane *plane;
+	struct drm_connector *conn;
+	struct drm_connector_state *conn_state;
+	int i, ret = 0;
+	unsigned plane_mask, disable_crtcs = false;
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	drm_modeset_acquire_init(&ctx, 0);
+	state->acquire_ctx = &ctx;
+
+retry:
+	plane_mask = 0;
+	ret = drm_modeset_lock_all_ctx(dev, &ctx);
+	if (ret)
+		goto unlock;
+
+	drm_for_each_plane(plane, dev) {
+		struct drm_plane_state *plane_state;
+
+		if (plane->state->fb != fb)
+			continue;
+
+		plane_state = drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state)) {
+			ret = PTR_ERR(plane_state);
+			goto unlock;
+		}
+
+		/*
+		 * Some drivers do not support keeping crtc active with the
+		 * primary plane disabled. If we fail to commit with -EINVAL
+		 * then we will try to perform the same commit but with all
+		 * crtc's disabled for primary planes as well.
+		 */
+		if (disable_crtcs && plane_state->crtc->primary == plane) {
+			struct drm_crtc_state *crtc_state;
+
+			crtc_state = drm_atomic_get_existing_crtc_state(state, plane_state->crtc);
+
+			ret = drm_atomic_add_affected_connectors(state, plane_state->crtc);
+			if (ret)
+				goto unlock;
+
+			crtc_state->active = false;
+			ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
+			if (ret)
+				goto unlock;
+		}
+
+		drm_atomic_set_fb_for_plane(plane_state, NULL);
+		ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
+		if (ret)
+			goto unlock;
+
+		plane_mask |= BIT(drm_plane_index(plane));
+
+		plane->old_fb = plane->fb;
+	}
+
+	/* This list is only not empty when disable_crtcs is set. */
+	for_each_connector_in_state(state, conn, conn_state, i) {
+		ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
+
+		if (ret)
+			goto unlock;
+	}
+
+	if (plane_mask)
+		ret = drm_atomic_commit(state);
+
+unlock:
+	if (plane_mask)
+		drm_atomic_clean_old_fb(dev, plane_mask, ret);
+
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+
+	drm_atomic_state_put(state);
+
+	if (ret == -EINVAL && !disable_crtcs) {
+		disable_crtcs = true;
+
+		state = drm_atomic_state_alloc(dev);
+		if (state) {
+			state->acquire_ctx = &ctx;
+			goto retry;
+		}
+		ret = -ENOMEM;
+	}
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+}
+
 int drm_mode_atomic_ioctl(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv)
 {

drivers/gpu/drm/drm_crtc_internal.h

@@ -183,6 +183,7 @@ int drm_atomic_get_property(struct drm_mode_object *obj,
 			    struct drm_property *property, uint64_t *val);
 int drm_mode_atomic_ioctl(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv);
+int drm_atomic_remove_fb(struct drm_framebuffer *fb);
 
 
 /* drm_plane.c */

drivers/gpu/drm/drm_framebuffer.c

@@ -773,6 +773,12 @@ void drm_framebuffer_remove(struct drm_framebuffer *fb)
 	 * in this manner.
 	 */
 	if (drm_framebuffer_read_refcount(fb) > 1) {
+		if (drm_drv_uses_atomic_modeset(dev)) {
+			int ret = drm_atomic_remove_fb(fb);
+			WARN(ret, "atomic remove_fb failed with %i\n", ret);
+			goto out;
+		}
+
 		drm_modeset_lock_all(dev);
 		/* remove from any CRTC */
 		drm_for_each_crtc(crtc, dev) {
@@ -790,6 +796,7 @@ void drm_framebuffer_remove(struct drm_framebuffer *fb)
 		drm_modeset_unlock_all(dev);
 	}
 
+out:
 	drm_framebuffer_unreference(fb);
 }
 EXPORT_SYMBOL(drm_framebuffer_remove);