waitforvsync.cpp revision d0566bc26fcf6ca396118701fa11900b627f2c09 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdint.h>
18#include <sys/types.h>
19
20#include <fcntl.h>
21#include <sys/ioctl.h>
22#include <linux/fb.h>
23#include <errno.h>
24#include <string.h>
25#include <stdio.h>
26
27#ifndef FBIO_WAITFORVSYNC
28#define FBIO_WAITFORVSYNC   _IOW('F', 0x20, __u32)
29#endif
30
31int main(int argc, char** argv) {
32    int fd = open("/dev/graphics/fb0", O_RDWR);
33    if (fd >= 0) {
34        do {
35            uint32_t crt = 0;
36           int err = ioctl(fd, FBIO_WAITFORVSYNC, &crt);
37           if (err < 0) {
38               printf("FBIO_WAITFORVSYNC error: %s\n", strerror(errno));
39               break;
40           }
41        } while(1);
42        close(fd);
43    }
44    return 0;
45}
46