drm/vblank: add return value to drm_crtc_wait_one_vblank()

Let drivers deal with the vblank wait failures if they so desire. If the
current warning backtrace gets toned down to a simple warning message,
the drivers may wish to add the backtrace themselves.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/7f2de4dd170771991756073f037c7ca043c3e746.1765290097.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: jnikula

drivers/gpu/drm/drm_vblank.c

@@ -1293,8 +1293,10 @@ EXPORT_SYMBOL(drm_crtc_vblank_put);
  * This waits for one vblank to pass on @crtc, using the irq driver interfaces.
  * It is a failure to call this when the vblank irq for @crtc is disabled, e.g.
  * due to lack of driver support or because the crtc is off.
+ *
+ * Returns: 0 on success, negative error on failures.
  */
-void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
+int drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 	int pipe = drm_crtc_index(crtc);
@@ -1305,7 +1307,7 @@ void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
 	ret = drm_vblank_get(dev, pipe);
 	if (drm_WARN(dev, ret, "vblank not available on crtc %i, ret=%i\n",
 		     pipe, ret))
-		return;
+		return ret;
 
 	last = drm_vblank_count(dev, pipe);
 
@@ -1316,6 +1318,8 @@ void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
 	drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe);
 
 	drm_vblank_put(dev, pipe);
+
+	return ret ? 0 : -ETIMEDOUT;
 }
 EXPORT_SYMBOL(drm_crtc_wait_one_vblank);
 

include/drm/drm_vblank.h

@@ -302,7 +302,7 @@ bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe);
 bool drm_crtc_handle_vblank(struct drm_crtc *crtc);
 int drm_crtc_vblank_get(struct drm_crtc *crtc);
 void drm_crtc_vblank_put(struct drm_crtc *crtc);
-void drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
+int drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
 void drm_crtc_vblank_off(struct drm_crtc *crtc);
 void drm_crtc_vblank_reset(struct drm_crtc *crtc);
 void drm_crtc_vblank_on_config(struct drm_crtc *crtc,