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ceb4a1ff9e
Compositors need to drive multiple connectors, each with its own vblank timings. For each device, there's one separate rendering loop per output. It's not possible to call liftoff_device_apply each time we want to submit a new frame to one output, because this could touch another's output state, submitting a new frame there in the process. When the other output will submit a new frame, it'll get EBUSY (can't submit two frames without waiting for vblank). Closes: https://github.com/emersion/libliftoff/issues/21
1.4 KiB
1.4 KiB
libliftoff
Lightweight hardware composer library for libdrm.
libliftoff eases the use of KMS planes from userspace without standing in your way. Users create "virtual planes" called layers, set KMS properties on them, and libliftoff will allocate planes for these layers if possible.
See the blog post introducing the project for more context.
Building
Depends on libdrm. Requires universal planes and atomic.
meson build/
ninja -C build/
Usage
See liftoff.h. Here's the general idea:
struct liftoff_device *device;
struct liftoff_output *output;
struct liftoff_layer *layer;
drmModeAtomicReq *req;
int ret;
device = liftoff_device_create(drm_fd);
output = liftoff_output_create(device, crtc_id);
layer = liftoff_layer_create(output);
liftoff_layer_set_property(layer, "FB_ID", fb_id);
/* Probably setup more properties and more layers */
req = drmModeAtomicAlloc();
if (!liftoff_output_apply(output, req)) {
perror("liftoff_output_apply");
exit(1);
}
ret = drmModeAtomicCommit(drm_fd, req, DRM_MODE_ATOMIC_NONBLOCK, NULL);
if (ret < 0) {
perror("drmModeAtomicCommit");
exit(1);
}
drmModeAtomicFree(req);
License
MIT