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Simple DirectMedia Layer
Copyright (C) 1997-2021 Sam Lantinga <>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
#include "../../SDL_internal.h"
#include "SDL_log.h"
#include "SDL_kmsdrmvideo.h"
#include "SDL_kmsdrmopengles.h"
#include "SDL_kmsdrmdyn.h"
/* EGL implementation of SDL OpenGL support */
KMSDRM_GLES_DefaultProfileConfig(_THIS, int *mask, int *major, int *minor)
/* if SDL was _also_ built with the Raspberry Pi driver (so we're
definitely a Pi device), default to GLES2. */
*major = 2;
*minor = 0;
KMSDRM_GLES_LoadLibrary(_THIS, const char *path) {
/* Just pretend you do this here, but don't do it until KMSDRM_CreateWindow(),
where we do the same library load we would normally do here.
because this gets called by SDL_CreateWindow() before KMSDR_CreateWindow(),
so gbm dev isn't yet created when this is called, AND we can't alter the
call order in SDL_CreateWindow(). */
#if 0
NativeDisplayType display = (NativeDisplayType)((SDL_VideoData *)_this->driverdata)->gbm_dev;
return SDL_EGL_LoadLibrary(_this, path, display, EGL_PLATFORM_GBM_MESA);
return 0;
KMSDRM_GLES_UnloadLibrary(_THIS) {
/* As with KMSDRM_GLES_LoadLibrary(), we define our own "dummy" unloading function
so we manually unload the library whenever we want. */
int KMSDRM_GLES_SetSwapInterval(_THIS, int interval) {
if (!_this->egl_data) {
return SDL_SetError("EGL not initialized");
if (interval == 0 || interval == 1) {
_this->egl_data->egl_swapinterval = interval;
} else {
return SDL_SetError("Only swap intervals of 0 or 1 are supported");
return 0;
KMSDRM_GLES_SwapWindow(_THIS, SDL_Window * window) {
SDL_WindowData *windata = ((SDL_WindowData *) window->driverdata);
SDL_DisplayData *dispdata = (SDL_DisplayData *) SDL_GetDisplayForWindow(window)->driverdata;
SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
KMSDRM_FBInfo *fb_info;
int ret, timeout;
/* Wait for confirmation that the next front buffer has been flipped, at which
point the previous front buffer can be released */
timeout = 0;
if (_this->egl_data->egl_swapinterval == 1) {
timeout = -1;
if (!KMSDRM_WaitPageFlip(_this, windata, timeout)) {
return 0;
/* Release the previous front buffer */
if (windata->bo) {
KMSDRM_gbm_surface_release_buffer(windata->gs, windata->bo);
windata->bo = NULL;
windata->bo = windata->next_bo;
/* Mark a buffer to becume the next front buffer.
This won't happen until pagelip completes. */
if (!(_this->egl_data->eglSwapBuffers(_this->egl_data->egl_display,
windata->egl_surface))) {
SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "eglSwapBuffers failed.");
return 0;
/* Lock the next front buffer so it can't be allocated as a back buffer */
windata->next_bo = KMSDRM_gbm_surface_lock_front_buffer(windata->gs);
if (!windata->next_bo) {
SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not lock GBM surface front buffer");
return 0;
/* Get the fb_info for the next front buffer. */
fb_info = KMSDRM_FBFromBO(_this, windata->next_bo);
if (!fb_info) {
return 0;
/* Do we have a modeset pending? If so, configure the new mode on the CRTC.
Has to be done before the upcoming pageflip issue, so the buffer with the
new size is big enough so the CRTC doesn't read out of bounds. */
if (dispdata->modeset_pending) {
/* This is fundamental. */
/* We can't display an fb smaller than the resolution currently configured */
/* on the CRTC, because the CRTC would be scanning out of bounds, and */
/* drmModeSetCrtc() would fail. */
/* A possible solution would be scaling on the primary plane with */
/* drmModeSetPlane(), but primary plane scaling is not supported in most */
/* LEGACY-only hardware, so never use drmModeSetPlane(). */
ret = KMSDRM_drmModeSetCrtc(viddata->drm_fd,
dispdata->crtc->crtc_id, fb_info->fb_id, 0, 0,
&dispdata->connector->connector_id, 1, &dispdata->mode);
if (ret) {
SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not set videomode on CRTC.");
return 0;
/* Issue pageflip on the next front buffer.
The pageflip will be done during the next vblank. */
ret = KMSDRM_drmModePageFlip(viddata->drm_fd, dispdata->crtc->crtc_id,
fb_info->fb_id, DRM_MODE_PAGE_FLIP_EVENT, &windata->waiting_for_flip);
if (_this->egl_data->egl_swapinterval == 1) {
if (ret == 0) {
windata->waiting_for_flip = SDL_TRUE;
} else {
SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not queue pageflip: %d", ret);
/* If we are in double-buffer mode, wait immediately for vsync
(as if we only had two buffers),
Run your SDL2 program with "SDL_KMSDRM_DOUBLE_BUFFER=1 <program_name>"
to enable this. */
if (_this->egl_data->egl_swapinterval == 1 && windata->double_buffer) {
KMSDRM_WaitPageFlip(_this, windata, -1);
return 0;
/* vi: set ts=4 sw=4 expandtab: */