掌機 - R36S - C/C++ - DRM/KMS - OpenGL ES 2.0 - Get Version

參考資訊：
https://gist.github.com/dvdhrm/5083553
https://www.kernel.org/doc/html/v4.15/gpu/drm-kms.html
https://github.com/grate-driver/libdrm/blob/master/xf86drmMode.h
https://gist.github.com/Miouyouyou/89e9fe56a2c59bce7d4a18a858f389ef

main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/mman.h>
#include <unistd.h>
#include <gbm.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>

static int fd = -1;
static int fb = -1;
static int waiting_for_flip = 0;

static drmModeRes *res = NULL;
static drmModeCrtc *crtc = NULL;
static drmModeEncoder *enc = NULL;
static drmModeConnector *conn = NULL;
 
static void flip_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data)
{
    *((int *)data) = 0;
}

drmEventContext evctx = {
    .version = DRM_EVENT_CONTEXT_VERSION,
    .page_flip_handler = flip_handler,
};

int main(int argc, char *argv[])
{
    const int w = 640;
    const int h = 480;
    const int bpp = 32;
    const int depth = 24;
 
    int i = 0;
    int j = 0;
 
    fd = open("/dev/dri/card0", O_RDWR | O_CLOEXEC);
    res = drmModeGetResources(fd);
    conn = drmModeGetConnector(fd, res->connectors[0]);
    enc = drmModeGetEncoder(fd, res->encoders[0]);
    crtc = drmModeGetCrtc(fd, res->crtcs[0]);

    struct gbm_device *gbm = gbm_create_device(fd);
	struct gbm_surface *gs = gbm_surface_create(gbm, crtc->mode.hdisplay, crtc->mode.vdisplay, GBM_FORMAT_XRGB8888, GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);

    EGLint egl_major = 0;
    EGLint egl_minor = 0;
    EGLint num_configs = 0;
    EGLConfig configs = {0};
    EGLDisplay display = EGL_NO_DISPLAY;
    EGLSurface surface = EGL_NO_SURFACE;
    EGLContext context = EGL_NO_CONTEXT;
    EGLint config_attribs[] = {
        EGL_SURFACE_TYPE,    EGL_WINDOW_BIT,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE,   8,  
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE,  8,  
        EGL_ALPHA_SIZE, 8,
        EGL_NONE
    };
    EGLint const context_attributes[] = {
        EGL_CONTEXT_CLIENT_VERSION, 2,
        EGL_NONE,
    };

    PFNEGLGETPLATFORMDISPLAYEXTPROC get_platform_display = NULL;
	get_platform_display = (void *)eglGetProcAddress("eglGetPlatformDisplayEXT");
    display = get_platform_display(EGL_PLATFORM_GBM_KHR, gbm, NULL);
    eglInitialize(display, &egl_major, &egl_minor);
    eglBindAPI(EGL_OPENGL_ES_API);
    eglChooseConfig(display, config_attribs, &configs, 1, &num_configs);
    surface = eglCreateWindowSurface(display, configs, gs, NULL);
    context = eglCreateContext(display, configs, EGL_NO_CONTEXT, context_attributes);
    eglMakeCurrent(display, surface, surface, context);

    printf("%s\n", glGetString(GL_VERSION));  

    eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(display, context);
    eglDestroySurface(display, surface);

    drmModeRmFB(fd, fb); 
    drmModeFreeCrtc(crtc);
    drmModeFreeEncoder(enc);
    drmModeFreeConnector(conn);
    drmModeFreeResources(res);
    close(fd);
    return 0;
}

編譯、執行

$ /opt/mini/bin/arm-linux-gnueabihf-gcc main.c -o main -I/opt/mini/arm-buildroot-linux-gnueabihf/sysroot/usr/include/drm -ldrm -lEGL -lGLESv2 -lgbm

root@rg351mp:/# kill -STOP `pidof emulationstation`
root@rg351mp:/# ./main
    OpenGL ES 3.2 v1.r13p0-01rel0.8747d14aec16ec21ac2b2da252c4ec5f