[PATCH] drm: document drm_mode_get_connector

[Simon Ser]

Document how to perform a forced probe, and when should user-space do it.

Signed-off-by: Simon Ser <contact at emersion.fr>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Pekka Paalanen <ppaalanen at gmail.com>
---
 include/uapi/drm/drm_mode.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 5ad10ab2a577..09647b799f39 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -368,6 +368,19 @@ enum drm_mode_subconnector {
 #define DRM_MODE_CONNECTOR_WRITEBACK	18
 #define DRM_MODE_CONNECTOR_SPI		19
 
+/**
+ * struct drm_mode_get_connector - get connector metadata
+ *
+ * If the @count_modes field is set to zero, the kernel will perform a forced
+ * probe on the connector to refresh the connector status, modes and EDID.
+ * A forced-probe can be slow and the ioctl will block.
+ *
+ * User-space shouldn't need to force-probe connectors in general: the kernel
+ * will automatically take care of probing connectors that don't support
+ * hot-plug detection when appropriate. However, user-space may force-probe
+ * connectors on user request (e.g. clicking a "Scan connectors" button, or
+ * opening a UI to manage screens).
+ */
 struct drm_mode_get_connector {
 
 	__u64 encoders_ptr;
-- 
2.29.2