3 * Copyright (C) 2018 Carlos Rafael Giani <dv@pseudoterminal.org>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
23 #include "../gstgl_fwd.h"
24 #include <gst/gl/gstglcontext.h>
25 #include <gst/gl/egl/gstglcontext_egl.h>
27 #include "gstgldisplay_gbm.h"
28 #include "gstglwindow_gbm_egl.h"
29 #include "gstgl_gbm_utils.h"
30 #include "../gstglwindow_private.h"
32 #define GST_CAT_DEFAULT gst_gl_window_debug
35 #define GST_GL_WINDOW_GBM_EGL_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), \
36 GST_TYPE_GL_WINDOW_GBM_EGL, GstGLWindowGBMEGLPrivate))
39 G_DEFINE_TYPE (GstGLWindowGBMEGL, gst_gl_window_gbm_egl, GST_TYPE_GL_WINDOW);
42 static guintptr gst_gl_window_gbm_egl_get_window_handle (GstGLWindow * window);
43 static guintptr gst_gl_window_gbm_egl_get_display (GstGLWindow * window);
44 static void gst_gl_window_gbm_egl_set_window_handle (GstGLWindow * window,
46 static void gst_gl_window_gbm_egl_close (GstGLWindow * window);
47 static void gst_gl_window_gbm_egl_draw (GstGLWindow * window);
49 static gboolean gst_gl_window_gbm_init_surface (GstGLWindowGBMEGL * window_egl);
50 static void gst_gl_window_gbm_egl_cleanup (GstGLWindowGBMEGL * window_egl);
55 gst_gl_window_gbm_egl_class_init (GstGLWindowGBMEGLClass * klass)
57 GstGLWindowClass *window_class = (GstGLWindowClass *) klass;
59 window_class->get_window_handle =
60 GST_DEBUG_FUNCPTR (gst_gl_window_gbm_egl_get_window_handle);
61 window_class->get_display =
62 GST_DEBUG_FUNCPTR (gst_gl_window_gbm_egl_get_display);
63 window_class->set_window_handle =
64 GST_DEBUG_FUNCPTR (gst_gl_window_gbm_egl_set_window_handle);
65 window_class->close = GST_DEBUG_FUNCPTR (gst_gl_window_gbm_egl_close);
66 window_class->draw = GST_DEBUG_FUNCPTR (gst_gl_window_gbm_egl_draw);
68 /* TODO: add support for set_render_rectangle (assuming this functionality
69 * is possible with libdrm/gbm) */
74 gst_gl_window_gbm_egl_init (GstGLWindowGBMEGL * window_gbm)
76 window_gbm->gbm_surf = NULL;
77 window_gbm->current_bo = NULL;
78 window_gbm->prev_bo = NULL;
79 window_gbm->waiting_for_flip = 0;
84 gst_gl_window_gbm_egl_get_window_handle (GstGLWindow * window)
86 GstGLWindowGBMEGL *window_egl = GST_GL_WINDOW_GBM_EGL (window);
88 /* This function is called in here, and not in the open()
89 * vmethod. The reason for this is explained inside the
90 * gst_gl_window_gbm_init_surface() function. */
91 if (window_egl->gbm_surf == NULL) {
92 if (!gst_gl_window_gbm_init_surface (window_egl))
96 return (guintptr) GST_GL_WINDOW_GBM_EGL (window)->gbm_surf;
101 gst_gl_window_gbm_egl_get_display (GstGLWindow * window)
103 return gst_gl_display_get_handle (window->display);
108 gst_gl_window_gbm_egl_set_window_handle (G_GNUC_UNUSED GstGLWindow * window,
109 G_GNUC_UNUSED guintptr handle)
111 /* TODO: Currently, it is unclear how to use external GBM buffer objects,
112 * since it is not defined how this would work together with DRM page flips
118 gst_gl_window_gbm_egl_close (GstGLWindow * window)
120 GstGLWindowGBMEGL *window_egl = GST_GL_WINDOW_GBM_EGL (window);
122 gst_gl_window_gbm_egl_cleanup (window_egl);
124 GST_GL_WINDOW_CLASS (gst_gl_window_gbm_egl_parent_class)->close (window);
129 _page_flip_handler (G_GNUC_UNUSED int fd, G_GNUC_UNUSED unsigned int frame,
130 G_GNUC_UNUSED unsigned int sec, G_GNUC_UNUSED unsigned int usec, void *data)
132 /* If we reach this point, it means the page flip has been completed.
133 * Signal this by clearing the flag so the poll() loop in draw_cb()
135 int *waiting_for_flip = data;
136 *waiting_for_flip = 0;
140 draw_cb (gpointer data)
142 GstGLWindowGBMEGL *window_egl = data;
143 GstGLWindow *window = GST_GL_WINDOW (window_egl);
144 GstGLContext *context = gst_gl_window_get_context (window);
145 GstGLContextClass *context_class = GST_GL_CONTEXT_GET_CLASS (context);
146 GstGLDisplayGBM *display = (GstGLDisplayGBM *) window->display;
147 struct gbm_bo *next_bo;
148 GstGLDRMFramebuffer *framebuf;
151 drmEventContext evctx = {
152 .version = DRM_EVENT_CONTEXT_VERSION,
153 .page_flip_handler = _page_flip_handler,
156 struct pollfd pfd = {
157 .fd = display->drm_fd,
162 /* Rendering, page flipping etc. are connect this way:
164 * The frames are stored in buffer objects (BOs). Inside the eglSwapBuffers()
165 * call, GBM creates new BOs if necessary. BOs can be "locked" for rendering,
166 * meaning that EGL cannot use them as a render target. If all available
167 * BOs are locked, the GBM code inside eglSwapBuffers() creates a new,
168 * unlocked one. We make use of this to implement triple buffering.
170 * There are 3 BOs in play:
172 * * next_bo: The BO we just rendered into.
173 * * current_bo: The currently displayed BO.
174 * * prev_bo: The previously displayed BO.
176 * current_bo and prev_bo are involed in page flipping. next_bo is not.
178 * Once rendering is done, the next_bo is retrieved and locked. Then, we
179 * wait until any ongoing page flipping finishes. Once it does, the
180 * current_bo is displayed on screen, and the prev_bo isn't anymore. At
181 * this point, it is safe to release the prev_bo, which unlocks it and
182 * makes it available again as a render target. Then we initiate the
183 * next page flipping; this time, we flip to next_bo. At that point,
184 * next_bo becomes current_bo, and current_bo becomes prev_bo.
188 * There is a special case at the beginning. There is no currently
189 * displayed BO at first, so we create an empty one to get the page
190 * flipping cycle going. Also, we use this first BO for setting up
193 if (window_egl->current_bo == NULL) {
194 /* Call eglSwapBuffers() to create a BO. */
195 context_class->swap_buffers (context);
197 /* Lock the BO so we get our first current_bo. */
198 window_egl->current_bo =
199 gbm_surface_lock_front_buffer (window_egl->gbm_surf);
200 framebuf = gst_gl_gbm_drm_fb_get_from_bo (window_egl->current_bo);
202 /* Configure CRTC to show this first BO. */
203 ret = drmModeSetCrtc (display->drm_fd, display->crtc_id, framebuf->fb_id,
204 0, 0, &(display->drm_mode_connector->connector_id), 1,
205 display->drm_mode_info);
208 GST_ERROR ("Could not set DRM CRTC: %s (%d)", g_strerror (errno), errno);
209 /* XXX: it is not possible to communicate the error to the pipeline */
214 /* Do the actual drawing */
216 window->draw (window->draw_data);
218 /* Let the context class call eglSwapBuffers(). As mentioned above,
219 * if necessary, this function creates a new unlocked framebuffer
220 * that can be used as render target. */
221 context_class->swap_buffers (context);
222 gst_object_unref (context);
224 next_bo = gbm_surface_lock_front_buffer (window_egl->gbm_surf);
225 framebuf = gst_gl_gbm_drm_fb_get_from_bo (next_bo);
226 GST_LOG ("rendered new frame into bo %p", (gpointer) next_bo);
228 /* Wait until any ongoing page flipping is done. After this is done,
229 * prev_bo is no longer involved in any page flipping, and can be
230 * safely released. */
231 while (window_egl->waiting_for_flip) {
232 ret = poll (&pfd, 1, -1);
235 GST_DEBUG ("Signal caught during poll() call");
237 GST_ERROR ("poll() failed: %s (%d)", g_strerror (errno), errno);
238 /* XXX: it is not possible to communicate errors and interruptions
243 drmHandleEvent (display->drm_fd, &evctx);
245 GST_LOG ("now showing bo %p", (gpointer) (window_egl->current_bo));
247 /* Release prev_bo, since it is no longer shown on screen. */
248 if (G_LIKELY (window_egl->prev_bo != NULL)) {
249 gbm_surface_release_buffer (window_egl->gbm_surf, window_egl->prev_bo);
250 GST_LOG ("releasing bo %p", (gpointer) (window_egl->prev_bo));
253 /* Presently, current_bo is shown on screen. Schedule the next page
254 * flip, this time flip to next_bo. The flip happens asynchronously, so
255 * we can continue and render etc. in the meantime. */
256 window_egl->waiting_for_flip = 1;
257 ret = drmModePageFlip (display->drm_fd, display->crtc_id, framebuf->fb_id,
258 DRM_MODE_PAGE_FLIP_EVENT, &(window_egl->waiting_for_flip));
260 /* NOTE: According to libdrm sources, the page is _not_
261 * considered flipped if drmModePageFlip() reports an error,
262 * so we do not update the priv->current_bo pointer here */
263 GST_ERROR ("Could not initialize GBM surface");
264 /* XXX: it is not possible to communicate the error to the pipeline */
268 /* At this point, we relabel the current_bo as the prev_bo.
269 * This may not actually be the case yet, but it will be soon - latest
270 * when the wait loop above finishes.
271 * Also, next_bo becomes current_bo. */
272 window_egl->prev_bo = window_egl->current_bo;
273 window_egl->current_bo = next_bo;
278 gst_gl_window_gbm_egl_draw (GstGLWindow * window)
280 gst_gl_window_send_message (window, (GstGLWindowCB) draw_cb, window);
285 gst_gl_window_gbm_init_surface (GstGLWindowGBMEGL * window_egl)
287 /* NOTE: This function cannot be called in the open() vmethod
288 * since context_egl->egl_display and context_egl->egl_config
289 * must have been set to valid values at this point, and open()
290 * is called _before_ these are set.
291 * Also, eglInitialize() is called _after_ the open() vmethod,
292 * which means that the return value of gbm_surface_create()
293 * contains some function pointers that are set to NULL and
294 * shouldn't be. This is because Mesa's eglInitialize() loads
295 * the DRI2 driver and the relevant functions aren't available
298 GstGLWindow *window = GST_GL_WINDOW (window_egl);
299 GstGLDisplayGBM *display = (GstGLDisplayGBM *) window->display;
300 drmModeModeInfo *drm_mode_info = display->drm_mode_info;
301 GstGLContext *context = gst_gl_window_get_context (window);
302 GstGLContextEGL *context_egl = GST_GL_CONTEXT_EGL (context);
305 /* With GBM-based EGL displays and configs, the native visual ID
306 * is a GBM pixel format. */
307 if (!eglGetConfigAttrib (context_egl->egl_display, context_egl->egl_config,
308 EGL_NATIVE_VISUAL_ID, &gbm_format)) {
309 GST_ERROR ("eglGetConfigAttrib failed: %s",
310 gst_egl_get_error_string (eglGetError ()));
314 /* Create a GBM surface that shall contain the BOs we are
315 * going to render into. */
316 window_egl->gbm_surf = gbm_surface_create (display->gbm_dev,
317 drm_mode_info->hdisplay, drm_mode_info->vdisplay, gbm_format,
318 GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
320 gst_gl_window_resize (window, drm_mode_info->hdisplay,
321 drm_mode_info->vdisplay);
323 GST_DEBUG ("Successfully created GBM surface");
330 gst_gl_window_gbm_egl_cleanup (GstGLWindowGBMEGL * window_egl)
332 if (window_egl->gbm_surf != NULL) {
333 if (window_egl->current_bo != NULL) {
334 gbm_surface_release_buffer (window_egl->gbm_surf, window_egl->current_bo);
335 window_egl->current_bo = NULL;
338 gbm_surface_destroy (window_egl->gbm_surf);
339 window_egl->gbm_surf = NULL;
344 /* Must be called in the gl thread */
346 gst_gl_window_gbm_egl_new (GstGLDisplay * display)
348 GstGLWindowGBMEGL *window_egl;
350 if ((gst_gl_display_get_handle_type (display) & GST_GL_DISPLAY_TYPE_GBM) == 0)
351 /* we require a GBM display to create windows */
354 window_egl = g_object_new (GST_TYPE_GL_WINDOW_GBM_EGL, NULL);