drm输出NV12数据时参数配置C代码

以下是一个简单的 C 代码示例，用于配置 DRM 输出 NV12 数据的参数：

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <drm/drm.h>
#include <drm/drm_mode.h>
#include <drm/drm_fourcc.h>

int main() {
    int fd = open("/dev/dri/card0", O_RDWR | O_CLOEXEC);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    struct drm_mode_create_dumb create_dumb = {
        .width = 1920,
        .height = 1080,
        .bpp = 16,
    };
    if (ioctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_dumb) < 0) {
        perror("DRM_IOCTL_MODE_CREATE_DUMB");
        return 1;
    }

    struct drm_mode_map_dumb map_dumb = {
        .handle = create_dumb.handle,
    };
    if (ioctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &map_dumb) < 0) {
        perror("DRM_IOCTL_MODE_MAP_DUMB");
        return 1;
    }

    uint32_t fourcc = DRM_FORMAT_NV12;
    struct drm_mode_create_dumb create_dumb_uv = {
        .width = create_dumb.width / 2,
        .height = create_dumb.height / 2,
        .bpp = 8,
        .flags = 0,
    };
    create_dumb_uv.size = create_dumb_uv.width * create_dumb_uv.height * create_dumb_uv.bpp / 8;
    create_dumb_uv.pitch = create_dumb_uv.width;
    create_dumb_uv.flags |= DRM_MODE_CREATE_DUMB_SCANOUT;
    create_dumb_uv.flags |= DRM_MODE_CREATE_DUMB_READONLY;
    create_dumb_uv.flags |= DRM_MODE_CREATE_DUMB_NOZERO;
    create_dumb_uv.flags |= DRM_MODE_CREATE_DUMB_FREED;
    if (fourcc == DRM_FORMAT_NV12) {
        create_dumb_uv.flags |= DRM_MODE_CREATE_DUMB_CMA_IMPORT;
    }
    if (ioctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_dumb_uv) < 0) {
        perror("DRM_IOCTL_MODE_CREATE_DUMB");
        return 1;
    }

    struct drm_mode_map_dumb map_dumb_uv = {
        .handle = create_dumb_uv.handle,
    };
    if (ioctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &map_dumb_uv) < 0) {
        perror("DRM_IOCTL_MODE_MAP_DUMB");
        return 1;
    }

    struct drm_mode_fb_cmd2 fb_cmd2 = {
        .fb_id = 0,
        .width = create_dumb.width,
        .height = create_dumb.height,
        .pixel_format = fourcc,
        .flags = 0,
        .handles = {create_dumb.handle, create_dumb_uv.handle},
        .pitches = {create_dumb.width * 2, create_dumb_uv.width},
        .offsets = {0, create_dumb.width * create_dumb.height},
    };
    if (ioctl(fd, DRM_IOCTL_MODE_ADDFB2, &fb_cmd2) < 0) {
        perror("DRM_IOCTL_MODE_ADDFB2");
        return 1;
    }

    // Do something with the framebuffer...

    if (ioctl(fd, DRM_IOCTL_MODE_RMFB, &fb_cmd2.fb_id) < 0) {
        perror("DRM_IOCTL_MODE_RMFB");
        return 1;
    }

    if (ioctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &create_dumb_uv) < 0) {
        perror("DRM_IOCTL_MODE_DESTROY_DUMB");
        return 1;
    }

    if (ioctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &create_dumb) < 0) {
        perror("DRM_IOCTL_MODE_DESTROY_DUMB");
        return 1;
    }

    close(fd);
    return 0;
}

这个示例代码使用 DRM API 来创建 NV12 格式的帧缓冲区，并将其添加到主显示器中。在实际使用中，您需要根据您的具体需求修改参数配置。