wlroots-hyprland/include/backend/drm/util.h
Simon Ser 0817c52a21 backend/drm: get rid of BO handle table
The BO handle table exists to avoid double-closing a BO handle,
which aren't reference-counted by the kernel. But if we can
guarantee that there is only ever a single ref for each BO handle,
then we don't need the BO handle table anymore.

This is possible if we create the handle right before the ADDFB2
IOCTL, and close the handle right after. The handles are very
short-lived and we don't need to track their lifetime.

Because of multi-planar FBs, we need to be a bit careful: some
FB planes might share the same handle. But with a small check, it's
easy to avoid double-closing the same handle (which wouldn't be a
big deal anyways).

There's one gotcha though: drmModeSetCursor2 takes a BO handle as
input. Saving the handles until drmModeSetCursor2 time would require
us to track BO handle lifetimes, so we wouldn't be able to get rid
of the BO handle table. As a workaround, use drmModeGetFB to turn the
FB ID back to a BO handle, call drmModeSetCursor2 and then immediately
close the BO handle. The overhead should be minimal since these IOCTLs
are pretty cheap.

Closes: https://github.com/swaywm/wlroots/issues/3164
2021-10-29 11:38:37 +02:00

46 lines
1.4 KiB
C

#ifndef BACKEND_DRM_UTIL_H
#define BACKEND_DRM_UTIL_H
#include <stdint.h>
#include <wlr/types/wlr_output.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
// Calculates a more accurate refresh rate (mHz) than what mode itself provides
int32_t calculate_refresh_rate(const drmModeModeInfo *mode);
// Populates the make/model/phys_{width,height} of output from the edid data
void parse_edid(struct wlr_output *restrict output, size_t len,
const uint8_t *data);
// Returns the string representation of a DRM output type
const char *conn_get_name(uint32_t type_id);
// Part of match_obj
enum {
UNMATCHED = (uint32_t)-1,
SKIP = (uint32_t)-2,
};
/*
* Tries to match some DRM objects with some other DRM resource.
* e.g. Match CRTCs with Encoders, CRTCs with Planes.
*
* objs contains a bit array which resources it can be matched with.
* e.g. Bit 0 set means can be matched with res[0]
*
* res contains an index of which objs it is matched with or UNMATCHED.
*
* This solution is left in out.
* Returns the total number of matched solutions.
*/
size_t match_obj(size_t num_objs, const uint32_t objs[static restrict num_objs],
size_t num_res, const uint32_t res[static restrict num_res],
uint32_t out[static restrict num_res]);
/**
* Close a GEM buffer handle.
*
* TODO: replace with drmCloseBufferHandle.
*/
void close_bo_handle(int drm_fd, uint32_t handle);
#endif