drm-legacy.c

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>

#include "common.h"
#include "drm-common.h"

static struct drm drm;

static void page_flip_handler(int fd, unsigned int frame,
		  unsigned int sec, unsigned int usec, void *data)
{
	/* suppress 'unused parameter' warnings */
	(void)fd, (void)frame, (void)sec, (void)usec;

	int *waiting_for_flip = data;
	*waiting_for_flip = 0;
}

static int legacy_run(const struct gbm *gbm, const struct egl *egl)
{
	fd_set fds;
	drmEventContext evctx = {
			.version = 2,
			.page_flip_handler = page_flip_handler,
	};
	struct gbm_bo *bo;
	struct drm_fb *fb;
	uint32_t i = 0;
	int ret;

	FD_ZERO(&fds);
	FD_SET(0, &fds);
	FD_SET(drm.fd, &fds);

	eglSwapBuffers(egl->display, egl->surface);
	bo = gbm_surface_lock_front_buffer(gbm->surface);
	fb = drm_fb_get_from_bo(bo);
	if (!fb) {
		fprintf(stderr, "Failed to get a new framebuffer BO\n");
		return -1;
	}

	/* set mode: */
	ret = drmModeSetCrtc(drm.fd, drm.crtc_id, fb->fb_id, 0, 0,
			&drm.connector_id, 1, drm.mode);
	if (ret) {
		printf("failed to set mode: %s\n", strerror(errno));
		return ret;
	}

	while (1) {
		struct gbm_bo *next_bo;
		int waiting_for_flip = 1;

		// TODO: wait for present?

		eglSwapBuffers(egl->display, egl->surface);
		next_bo = gbm_surface_lock_front_buffer(gbm->surface);
		fb = drm_fb_get_from_bo(next_bo);
		if (!fb) {
			fprintf(stderr, "Failed to get a new framebuffer BO\n");
			return -1;
		}

		/*
		 * Here you could also update drm plane layers if you want
		 * hw composition
		 */

		ret = drmModePageFlip(drm.fd, drm.crtc_id, fb->fb_id,
				DRM_MODE_PAGE_FLIP_EVENT, &waiting_for_flip);
		if (ret) {
			printf("failed to queue page flip: %s\n", strerror(errno));
			return -1;
		}

		while (waiting_for_flip) {
			ret = select(drm.fd + 1, &fds, NULL, NULL, NULL);
			if (ret < 0) {
				printf("select err: %s\n", strerror(errno));
				return ret;
			} else if (ret == 0) {
				printf("select timeout!\n");
				return -1;
			} else if (FD_ISSET(0, &fds)) {
				printf("user interrupted!\n");
				break;
			}
			drmHandleEvent(drm.fd, &evctx);
		}

		/* release last buffer to render on again: */
		gbm_surface_release_buffer(gbm->surface, bo);
		bo = next_bo;
	}

	return 0;
}

const struct drm * init_drm_legacy(const char *device)
{
	int ret;

	ret = init_drm(&drm, device);
	if (ret)
		return NULL;

	drm.run = legacy_run;

	return &drm;
}