kms: defer setting crtc modes until first swap buffers

Instead of creating a dummy framebuffer allocation just so we can setup
crtc modes during display_setup we now wait until the first swap_buffers
request before setting up the crtc modes.

This patch also adds a cogl_kms_display_queue_modes_reset() function
that allows developers to explicitly queue a reset of the crtc modes.
The idea is that applications that handle VT switching can use this for
VT enter events to explicitly ensure their mode is restored since modes
are often not automatically restored correctly.

cogl/Makefile.am

@@ -398,7 +398,8 @@ cogl_sources_c += \
 endif
 if SUPPORT_EGL_PLATFORM_KMS
 cogl_public_h += \
-	$(srcdir)/cogl-kms-renderer.h
+	$(srcdir)/cogl-kms-renderer.h \
+	$(srcdir)/cogl-kms-display.h
 cogl_sources_c += \
 	$(srcdir)/winsys/cogl-winsys-egl-kms.c \
 	$(srcdir)/winsys/cogl-winsys-egl-kms-private.h

cogl/cogl-kms-display.h

@@ -0,0 +1,58 @@
+
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2012 Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <cogl/cogl.h> can be included directly."
+#endif
+
+#ifndef __COGL_KMS_DISPLAY_H__
+#define __COGL_KMS_DISPLAY_H__
+
+#include <cogl/cogl-types.h>
+#include <cogl/cogl-display.h>
+
+G_BEGIN_DECLS
+
+/**
+ * cogl_kms_display_queue_modes_reset:
+ * @display: A #CoglDisplay
+ *
+ * Asks Cogl to explicitly reset the crtc output modes at the next
+ * #CoglOnscreen swap_buffers request. For applications that support
+ * VT switching they may want to re-assert the output modes when
+ * switching back to the applications VT since the modes are often not
+ * correctly restored automatically.
+ *
+ * <note>The @display must have been either explicitly setup via
+ * cogl_display_setup() or implicitily setup by having created a
+ * context using the @display</note>
+ *
+ * Since: 1.10
+ * Stability: unstable
+ */
+void
+cogl_kms_display_queue_modes_reset (CoglDisplay *display);
+
+G_END_DECLS
+#endif /* __COGL_KMS_DISPLAY_H__ */

cogl/cogl.h

@@ -100,6 +100,7 @@ typedef struct _CoglFramebuffer CoglFramebuffer;
 #include <cogl/cogl-poll.h>
 #if defined (COGL_HAS_EGL_PLATFORM_KMS_SUPPORT)
 #include <cogl/cogl-kms-renderer.h>
+#include <cogl/cogl-kms-display.h>
 #endif
 #if defined (COGL_HAS_EGL_PLATFORM_WAYLAND_SUPPORT)
 #include <cogl/cogl-wayland-renderer.h>

cogl/winsys/cogl-winsys-egl-kms.c

@@ -75,6 +75,7 @@ typedef struct _CoglDisplayKMS
 {
   GList *outputs;
   int width, height;
+  gboolean pending_set_crtc;
   gboolean pending_swap_notify;
 } CoglDisplayKMS;
 
@@ -355,23 +356,26 @@ find_output (int _index,
   return output;
 }
 
-static gboolean
-set_crtc (int fd, uint32_t fb_id, CoglOutputKMS *output, GError **error)
+static void
+setup_crtc_modes (CoglDisplay *display, int fb_id)
 {
-  int ret = drmModeSetCrtc (fd,
-                            output->encoder->crtc_id,
-                            fb_id, 0, 0,
-                            &output->connector->connector_id, 1,
-                            &output->mode);
-  if (ret)
-    {
-      g_set_error (error, COGL_WINSYS_ERROR,
-                   COGL_WINSYS_ERROR_INIT,
-                   "Failed to set mode %s: %m", output->mode.name);
-      return FALSE;
-    }
+  CoglDisplayEGL *egl_display = display->winsys;
+  CoglDisplayKMS *kms_display = egl_display->platform;
+  CoglRendererEGL *egl_renderer = display->renderer->winsys;
+  CoglRendererKMS *kms_renderer = egl_renderer->platform;
+  GList *l;
 
-  return TRUE;
+  for (l = kms_display->outputs; l; l = l->next)
+    {
+      CoglOutputKMS *output = l->data;
+      int ret = drmModeSetCrtc (kms_renderer->fd,
+                                output->encoder->crtc_id,
+                                fb_id, 0, 0,
+                                &output->connector->connector_id, 1,
+                                &output->mode);
+      if (ret)
+        g_warning ("Failed to set crtc mode %s: %m", output->mode.name);
+    }
 }
 
 static gboolean
@@ -472,37 +476,12 @@ _cogl_winsys_egl_display_setup (CoglDisplay *display,
   else
     output0->mode = output0->modes[0];
 
-  width = output0->mode.hdisplay;
-  height = output0->mode.vdisplay;
+  kms_display->width = output0->mode.hdisplay;
+  kms_display->height = output0->mode.vdisplay;
 
-  bo = gbm_bo_create (kms_renderer->gbm,
-                      width, height, GBM_BO_FORMAT_XRGB8888, GBM_BO_USE_SCANOUT);
-  pitch = gbm_bo_get_pitch (bo);
-  handle = gbm_bo_get_handle (bo).u32;
-  if (drmModeAddFB (kms_renderer->fd,
-                    width,
-                    height,
-                    24, /* depth */
-                    32, /* bpp */
-                    pitch,
-                    handle,
-                    &fb_id) != 0)
-    {
-      g_set_error (error, COGL_WINSYS_ERROR,
-                   COGL_WINSYS_ERROR_INIT,
-                   "Failed to create initial framebuffer");
-      return FALSE;
-    }
-
-  if (!set_crtc (kms_renderer->fd, fb_id, output0, error))
-    return FALSE;
-
-  if (mirror)
-    if (!set_crtc (kms_renderer->fd, fb_id, output1, error))
-      return FALSE;
-
-  kms_display->width = width;
-  kms_display->height = height;
+  /* We defer setting the crtc modes until the first swap_buffers request of a
+   * CoglOnscreen framebuffer. */
+  kms_display->pending_set_crtc = TRUE;
 
   return TRUE;
 }
@@ -702,6 +681,14 @@ _cogl_winsys_onscreen_swap_buffers (CoglOnscreen *onscreen)
       return;
     }
 
+  /* If this is the first framebuffer to be presented then we now setup the
+   * crtc modes... */
+  if (kms_display->pending_set_crtc)
+    {
+      setup_crtc_modes (context->display, kms_onscreen->next_fb_id);
+      kms_display->pending_set_crtc = FALSE;
+    }
+
   flip = g_slice_new0 (CoglFlipKMS);
   flip->onscreen = onscreen;
 
@@ -979,3 +966,14 @@ cogl_kms_renderer_get_drm_fd (CoglRenderer *renderer)
   else
     return -1;
 }
+
+void
+cogl_kms_display_queue_modes_reset (CoglDisplay *display)
+{
+  if (display->setup)
+    {
+      CoglDisplayEGL *egl_display = display->winsys;
+      CoglDisplayKMS *kms_display = egl_display->platform;
+      kms_display->pending_set_crtc = TRUE;
+    }
+}