sync code with last improvements from OpenBSD

lib/libdrm/man/drmHandleEvent.3.rst

@@ -0,0 +1,62 @@
+==============
+drmHandleEvent
+==============
+
+-----------------------------------
+read and process pending DRM events
+-----------------------------------
+
+:Date: September 2012
+:Manual section: 3
+:Manual group: Direct Rendering Manager
+
+Synopsis
+========
+
+``#include <xf86drm.h>``
+
+``int drmHandleEvent(int fd, drmEventContextPtr evctx);``
+
+Description
+===========
+
+``drmHandleEvent`` processes outstanding DRM events on the DRM
+file-descriptor passed as ``fd``. This function should be called after
+the DRM file-descriptor has polled readable; it will read the events and
+use the passed-in ``evctx`` structure to call function pointers with the
+parameters noted below:
+
+::
+
+   typedef struct _drmEventContext {
+       int version;
+       void (*vblank_handler) (int fd,
+                               unsigned int sequence,
+                               unsigned int tv_sec,
+                               unsigned int tv_usec,
+                               void *user_data)
+       void (*page_flip_handler) (int fd,
+                                  unsigned int sequence,
+                                  unsigned int tv_sec,
+                                  unsigned int tv_usec,
+                                  void *user_data)
+   } drmEventContext, *drmEventContextPtr;
+
+Return Value
+============
+
+``drmHandleEvent`` returns 0 on success, or if there is no data to
+read from the file-descriptor. Returns -1 if the read on the
+file-descriptor fails or returns less than a full event record.
+
+Reporting Bugs
+==============
+
+Bugs in this function should be reported to
+https://gitlab.freedesktop.org/mesa/drm/-/issues
+
+See Also
+========
+
+**drm**\ (7), **drm-kms**\ (7), **drmModePageFlip**\ (3),
+**drmWaitVBlank**\ (3)