drm/qxl: reapply cursor after SetCrtc calls

The qxl driver currently destroys and recreates the
qxl "primary" any time the first crtc is set.

A side-effect of destroying the primary is mouse state
associated with the crtc is lost, which leads to
disappearing mouse cursors on wayland sessions.

This commit changes the driver to reapply the cursor
any time SetCrtc is called. It achieves this by keeping
a reference to the cursor bo on the qxl_crtc struct.

Signed-off-by: Ray Strode <rstrode@redhat.com>
Message-id: 1473433745-11016-1-git-send-email-halfline@gmail.com

https://bugzilla.redhat.com/show_bug.cgi?id=1200901
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/qxl/qxl_display.c

@@ -211,6 +211,7 @@ static void qxl_crtc_destroy(struct drm_crtc *crtc)
 	struct qxl_crtc *qxl_crtc = to_qxl_crtc(crtc);
 
 	drm_crtc_cleanup(crtc);
+	qxl_bo_unref(&qxl_crtc->cursor_bo);
 	kfree(qxl_crtc);
 }
 
@@ -296,6 +297,52 @@ qxl_hide_cursor(struct qxl_device *qdev)
 	return 0;
 }
 
+static int qxl_crtc_apply_cursor(struct drm_crtc *crtc)
+{
+	struct qxl_crtc *qcrtc = to_qxl_crtc(crtc);
+	struct drm_device *dev = crtc->dev;
+	struct qxl_device *qdev = dev->dev_private;
+	struct qxl_cursor_cmd *cmd;
+	struct qxl_release *release;
+	int ret = 0;
+
+	if (!qcrtc->cursor_bo)
+		return 0;
+
+	ret = qxl_alloc_release_reserved(qdev, sizeof(*cmd),
+					 QXL_RELEASE_CURSOR_CMD,
+					 &release, NULL);
+	if (ret)
+		return ret;
+
+	ret = qxl_release_list_add(release, qcrtc->cursor_bo);
+	if (ret)
+		goto out_free_release;
+
+	ret = qxl_release_reserve_list(release, false);
+	if (ret)
+		goto out_free_release;
+
+	cmd = (struct qxl_cursor_cmd *)qxl_release_map(qdev, release);
+	cmd->type = QXL_CURSOR_SET;
+	cmd->u.set.position.x = qcrtc->cur_x + qcrtc->hot_spot_x;
+	cmd->u.set.position.y = qcrtc->cur_y + qcrtc->hot_spot_y;
+
+	cmd->u.set.shape = qxl_bo_physical_address(qdev, qcrtc->cursor_bo, 0);
+
+	cmd->u.set.visible = 1;
+	qxl_release_unmap(qdev, release, &cmd->release_info);
+
+	qxl_push_cursor_ring_release(qdev, release, QXL_CMD_CURSOR, false);
+	qxl_release_fence_buffer_objects(release);
+
+	return ret;
+
+out_free_release:
+	qxl_release_free(qdev, release);
+	return ret;
+}
+
 static int qxl_crtc_cursor_set2(struct drm_crtc *crtc,
 				struct drm_file *file_priv,
 				uint32_t handle,
@@ -400,7 +447,8 @@ static int qxl_crtc_cursor_set2(struct drm_crtc *crtc,
 	}
 	drm_gem_object_unreference_unlocked(obj);
 
-	qxl_bo_unref(&cursor_bo);
+	qxl_bo_unref (&qcrtc->cursor_bo);
+	qcrtc->cursor_bo = cursor_bo;
 
 	return ret;
 
@@ -655,6 +703,12 @@ static int qxl_crtc_mode_set(struct drm_crtc *crtc,
 			   bo->surf.stride, bo->surf.format);
 		qxl_io_create_primary(qdev, 0, bo);
 		bo->is_primary = true;
+
+		ret = qxl_crtc_apply_cursor(crtc);
+		if (ret) {
+			DRM_ERROR("could not set cursor after modeset");
+			ret = 0;
+		}
 	}
 
 	if (bo->is_primary) {

drivers/gpu/drm/qxl/qxl_drv.h

@@ -137,6 +137,7 @@ struct qxl_crtc {
 	int cur_y;
 	int hot_spot_x;
 	int hot_spot_y;
+	struct qxl_bo *cursor_bo;
 };
 
 struct qxl_output {