Merge tag 'drm-misc-fixes-2018-02-21' of git://anongit.freedesktop.org/drm/drm-misc...

[sfrench/cifs-2.6.git] / drivers / gpu / drm / drm_probe_helper.c

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 6dc2dde5b67202d43ad17438c8feb84eda010f41..00b8445ba8192b63bf6015eb1442342c39b47378 100644 (file)
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -216,8 +216,7 @@ enum drm_mode_status drm_connector_mode_valid(struct drm_connector *connector,
  * suspend/resume.
  *
  * Drivers can call this helper from their device resume implementation. It is
- * an error to call this when the output polling support has not yet been set
- * up.
+ * not an error to call this even when output polling isn't enabled.
  *
  * Note that calls to enable and disable polling must be strictly ordered, which
  * is automatically the case when they're only call from suspend/resume
@@ -654,6 +653,26 @@ out:
                schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
 }
 
+/**
+ * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
+ *
+ * Determine if %current task is an output poll worker.  This can be used
+ * to select distinct code paths for output polling versus other contexts.
+ *
+ * One use case is to avoid a deadlock between the output poll worker and
+ * the autosuspend worker wherein the latter waits for polling to finish
+ * upon calling drm_kms_helper_poll_disable(), while the former waits for
+ * runtime suspend to finish upon calling pm_runtime_get_sync() in a
+ * connector ->detect hook.
+ */
+bool drm_kms_helper_is_poll_worker(void)
+{
+       struct work_struct *work = current_work();
+
+       return work && work->func == output_poll_execute;
+}
+EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
+
 /**
  * drm_kms_helper_poll_disable - disable output polling
  * @dev: drm_device