[KMS/DRM] Fix fullscreen to windowed transition. Fix aspect ratio correction without using planes.

src/video/kmsdrm/SDL_kmsdrmopengles.c

@@ -28,6 +28,7 @@
 #include "SDL_kmsdrmvideo.h"
 #include "SDL_kmsdrmopengles.h"
 #include "SDL_kmsdrmdyn.h"
+#include <errno.h>
 
 #ifndef EGL_PLATFORM_GBM_MESA
 #define EGL_PLATFORM_GBM_MESA 0x31D7
@@ -70,6 +71,8 @@ KMSDRM_GLES_UnloadLibrary(_THIS) {
 SDL_EGL_CreateContext_impl(KMSDRM)
 
 int KMSDRM_GLES_SetSwapInterval(_THIS, int interval) {
+
+    /*
     if (!_this->egl_data) {
         return SDL_SetError("EGL not initialized");
     }
@@ -78,11 +81,23 @@ int KMSDRM_GLES_SetSwapInterval(_THIS, int interval) {
         _this->egl_data->egl_swapinterval = interval;
     } else {
         return SDL_SetError("Only swap intervals of 0 or 1 are supported");
-    }
+    }*/
+
+    /* Issuing a new pageflip before the previous has completed
+       causes drmModePageFlip() to return EBUSY errors. Don't do it. */
+    _this->egl_data->egl_swapinterval = 1;
 
     return 0;
 }
 
+/* Check if we need to re-create the GBM and EGL surfaces and setup a new mode on the CRTC
+   matching the new GBM surface size so the buffers from these surfaces can be displayed
+   on the CRTC (remember we need the CRTC mode and the buffer size to match). */
+/*KMSDRM_CheckKMSDRM (_THIS, window) {
+
+
+}*/
+
 int
 KMSDRM_GLES_SwapWindow(_THIS, SDL_Window * window) {
     SDL_WindowData *windata = ((SDL_WindowData *) window->driverdata);
@@ -117,56 +132,92 @@ KMSDRM_GLES_SwapWindow(_THIS, SDL_Window * window) {
         return 0;
     }
 
-    /* Lock the next front buffer so it can't be allocated as a back buffer */
+    /* From the GBM surface, get the next BO to become the next front buffer,
+       and lock it so it can't be allocated as a back buffer (to prevent EGL
+       from drawing into it!) */
     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. */
+    /* Get an actual usable fb for the next front buffer. */
     fb_info = KMSDRM_FBFromBO(_this, windata->next_bo);
     if (!fb_info) {
         return 0;
     }
 
+#if 0
+    /* Get an actual usable fb (of the specified dimensions) form the BO,
+       so we can pass it to the CRTC. */
+    fb_info = KMSDRM_FBFromBO2(_this, windata->next_bo, window->w, window->h);
+    if (!fb_info) {
+        return 0;
+    }
+#endif
+
+#if 0
+    /* If the window size does not match the current videomode configured on the CRTC,
+       update the current video mode and configure the new mode on the CRTC.  */
+    if (dispdata->mode.hdisplay != window->w || dispdata->mode.vdisplay != window->h) { 
+        for (int i = 0; i < dispdata->connector->count_modes; i++) {
+            drmModeModeInfo mode = dispdata->connector->modes[i] ;
+            if (mode.hdisplay == window->w && mode.vdisplay == window->h) {
+                dispdata->mode = mode;
+	        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 mode on CRTC.");
+		    printf("********Could not set mode on CRTC.\n");
+                }
+                return 0;
+            }
+        }
+        return 0;
+    }
+#endif
+
+#if 0
+    /* Get an actual usable fb for the next front buffer. */
+    fb_info = KMSDRM_FBFromBO(_this, windata->next_bo);
+    if (!fb_info) {
+        return 0;
+    }
+#endif
+
+#if 1 
     /* 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);
 
+        dispdata->modeset_pending = SDL_FALSE;
+
         if (ret) {
             SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not set videomode on CRTC.");
-
         }
+
         return 0;
     }
+#endif
 
     /* 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) {
+    if (ret == 0) {
+        if (_this->egl_data->egl_swapinterval == 1) {
 	    windata->waiting_for_flip = SDL_TRUE;
-	} else {
-	    SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not queue pageflip: %d", ret);
-	}
+        }
+    } else {
+	SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not queue pageflip: %d", ret);
     }
 
     /* If we are in double-buffer mode, wait immediately for vsync

src/video/kmsdrm/SDL_kmsdrmsym.h

@@ -45,6 +45,16 @@ SDL_KMSDRM_SYM(drmModeResPtr,drmModeGetResources,(int fd))
 SDL_KMSDRM_SYM(int,drmModeAddFB,(int fd, uint32_t width, uint32_t height, uint8_t depth,
                                  uint8_t bpp, uint32_t pitch, uint32_t bo_handle,
                                  uint32_t *buf_id))
+
+SDL_KMSDRM_SYM(int,drmModeAddFB2,(int fd, uint32_t width, uint32_t height,
+                                  uint32_t pixel_format,
+                                  uint32_t bo_handles[4],
+                                  uint32_t pitches[4],
+                                  uint32_t offsets[4],
+                                  uint32_t * buf_id,
+                                  uint32_t flags 
+))
+
 SDL_KMSDRM_SYM(int,drmModeRmFB,(int fd, uint32_t bufferId))
 SDL_KMSDRM_SYM(drmModeFBPtr,drmModeGetFB,(int fd, uint32_t buf))
 SDL_KMSDRM_SYM(drmModeCrtcPtr,drmModeGetCrtc,(int fd, uint32_t crtcId))
@@ -91,6 +101,8 @@ SDL_KMSDRM_SYM(struct gbm_device *,gbm_create_device,(int fd))
 SDL_KMSDRM_SYM(unsigned int,gbm_bo_get_width,(struct gbm_bo *bo))
 SDL_KMSDRM_SYM(unsigned int,gbm_bo_get_height,(struct gbm_bo *bo))
 SDL_KMSDRM_SYM(uint32_t,gbm_bo_get_stride,(struct gbm_bo *bo))
+SDL_KMSDRM_SYM(uint32_t,gbm_bo_get_format,(struct gbm_bo *bo))
+SDL_KMSDRM_SYM(uint32_t,gbm_bo_get_offset,(struct gbm_bo *bo, int plane))
 SDL_KMSDRM_SYM(union gbm_bo_handle,gbm_bo_get_handle,(struct gbm_bo *bo))
 SDL_KMSDRM_SYM(int,gbm_bo_write,(struct gbm_bo *bo, const void *buf, size_t count))
 SDL_KMSDRM_SYM(struct gbm_device *,gbm_bo_get_device,(struct gbm_bo *bo))

src/video/kmsdrm/SDL_kmsdrmvideo.c

@@ -332,6 +332,115 @@ KMSDRM_FBFromBO(_THIS, struct gbm_bo *bo)
     return fb_info;
 }
 
+#if 0
+/* Get an actual usable fb from a BO, specifying the size of the desired fb. */
+KMSDRM_FBInfo *
+KMSDRM_FBFromBO2(_THIS, struct gbm_bo *bo, int width, int height)
+{
+    SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
+    int ret;
+    Uint32 stride, handle;
+
+    uint32_t format, strides[4] = {0}, handles[4] = {0}, offsets[4] = {0}; 
+
+    /* Check for an existing framebuffer */
+    KMSDRM_FBInfo *fb_info = (KMSDRM_FBInfo *)KMSDRM_gbm_bo_get_user_data(bo);
+
+    if (fb_info) {
+        /* TODO We used to simply return the old fb_info if there was one here.
+           Now free it AND the actual buffer IF the sizes have changed (maybe
+           add them to fb_info? to avoid leaking.)*/
+        SDL_free(fb_info);
+    }
+
+    /* Create a structure that contains enough info to remove the framebuffer
+       when the backing buffer is destroyed */
+    fb_info = (KMSDRM_FBInfo *)SDL_calloc(1, sizeof(KMSDRM_FBInfo));
+
+    if (!fb_info) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+
+    fb_info->drm_fd = viddata->drm_fd;
+
+#if 0
+    /* Create framebuffer object for the buffer */
+    stride = KMSDRM_gbm_bo_get_stride(bo);
+    handle = KMSDRM_gbm_bo_get_handle(bo).u32;
+    ret = KMSDRM_drmModeAddFB(viddata->drm_fd, width, height, 24, 32, stride, handle,
+                                  &fb_info->fb_id);
+#endif
+
+    handles[0] = KMSDRM_gbm_bo_get_handle(bo).u32;
+    strides[0] = KMSDRM_gbm_bo_get_stride(bo);
+    offsets[0] = KMSDRM_gbm_bo_get_offset(bo, 0);
+    format = KMSDRM_gbm_bo_get_format(bo);
+
+    ret = KMSDRM_drmModeAddFB2(viddata->drm_fd, width, height, format,
+        handles, strides, offsets, &fb_info->fb_id, 0);
+
+
+    if (ret) {
+      SDL_free(fb_info);
+      return NULL;
+    }
+
+    /* Associate our DRM framebuffer with this buffer object */
+    KMSDRM_gbm_bo_set_user_data(bo, fb_info, KMSDRM_FBDestroyCallback);
+
+    return fb_info;
+}
+#endif
+
+#if 0
+/* Get an actual usable fb from a BO, specifying the size of the desired fb. */
+KMSDRM_FBInfo *
+KMSDRM_FBFromBO2(_THIS, struct gbm_bo *bo, int width, int height)
+{
+    SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
+    int ret;
+    Uint32 stride, handle;
+
+    /* Check for an existing framebuffer */
+    KMSDRM_FBInfo *fb_info = (KMSDRM_FBInfo *)KMSDRM_gbm_bo_get_user_data(bo);
+
+    if (fb_info) {
+        /* TODO We used to simply return the old fb_info if there was one here.
+           Now free it AND the actual buffer IF the sizes have changed (maybe
+           add them to fb_info? to avoid leaking.)*/
+        SDL_free(fb_info);
+    }
+
+    /* Create a structure that contains enough info to remove the framebuffer
+       when the backing buffer is destroyed */
+    fb_info = (KMSDRM_FBInfo *)SDL_calloc(1, sizeof(KMSDRM_FBInfo));
+
+    if (!fb_info) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+
+    fb_info->drm_fd = viddata->drm_fd;
+
+    /* Create framebuffer object for the buffer */
+    stride = KMSDRM_gbm_bo_get_stride(bo);
+    handle = KMSDRM_gbm_bo_get_handle(bo).u32;
+    ret = KMSDRM_drmModeAddFB(viddata->drm_fd, width, height, 24, 32, stride, handle,
+                                  &fb_info->fb_id);
+
+    if (ret) {
+      SDL_free(fb_info);
+      return NULL;
+    }
+
+    /* Associate our DRM framebuffer with this buffer object */
+    KMSDRM_gbm_bo_set_user_data(bo, fb_info, KMSDRM_FBDestroyCallback);
+
+    return fb_info;
+}
+#endif
+
 static void
 KMSDRM_FlipHandler(int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data)
 {
@@ -376,6 +485,21 @@ KMSDRM_WaitPageFlip(_THIS, SDL_WindowData *windata, int timeout) {
     return SDL_TRUE;
 }
 
+/* Given w and h, returns a DRM video mode from the modes available on the connector.
+   Returns NULL if no mode matching the specified size is found. */
+drmModeModeInfo*
+KMSDRM_GetConnectorMode(drmModeConnector *connector, uint32_t width, uint32_t height) {
+    int i = 0;
+    for (i = 0; i < connector->count_modes; i++) {
+	if (connector->modes[i].hdisplay == width &&
+            connector->modes[i].vdisplay == height)
+        {
+	    return &connector->modes[i];
+	}
+    }
+    return NULL;
+}
+
 /*****************************************************************************/
 /* SDL Video and Display initialization/handling functions                   */
 /* _this is a SDL_VideoDevice *                                              */
@@ -413,9 +537,8 @@ int KMSDRM_DisplayDataInit (_THIS, SDL_DisplayData *dispdata) {
     int ret = 0;
     unsigned i,j;
 
-    dispdata->modeset_pending = SDL_FALSE;
     dispdata->gbm_init = SDL_FALSE;
-
+    dispdata->modeset_pending = SDL_FALSE;
     dispdata->cursor_bo = NULL;
 
     /* Open /dev/dri/cardNN (/dev/drmN if on OpenBSD) */
@@ -693,6 +816,8 @@ KMSDRM_DestroySurfaces(_THIS, SDL_Window *window)
     }
 }
 
+/* This determines the size of the fb, which comes from the GBM surface
+   that we create here. */
 int
 KMSDRM_CreateSurfaces(_THIS, SDL_Window * window)
 {
@@ -701,7 +826,6 @@ KMSDRM_CreateSurfaces(_THIS, SDL_Window * window)
     SDL_DisplayData *dispdata = (SDL_DisplayData *) SDL_GetDisplayForWindow(window)->driverdata;
     uint32_t surface_fmt = GBM_FORMAT_ARGB8888;
     uint32_t surface_flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
-    uint32_t width, height;
 
     EGLContext egl_context;
 
@@ -714,16 +838,6 @@ KMSDRM_CreateSurfaces(_THIS, SDL_Window * window)
         KMSDRM_DestroySurfaces(_this, window);
     }
 
-    if ( ((window->flags & SDL_WINDOW_FULLSCREEN_DESKTOP) == SDL_WINDOW_FULLSCREEN_DESKTOP)
-      || ((window->flags & SDL_WINDOW_FULLSCREEN) == SDL_WINDOW_FULLSCREEN))
-    {
-        width = dispdata->mode.hdisplay;
-        height = dispdata->mode.vdisplay;
-    } else {
-        width = window->w;
-        height = window->h;
-    }
-
     if (!KMSDRM_gbm_device_is_format_supported(viddata->gbm_dev,
              surface_fmt, surface_flags)) {
         SDL_LogWarn(SDL_LOG_CATEGORY_VIDEO,
@@ -731,7 +845,7 @@ KMSDRM_CreateSurfaces(_THIS, SDL_Window * window)
     }
 
     windata->gs = KMSDRM_gbm_surface_create(viddata->gbm_dev,
-                      width, height, surface_fmt, surface_flags);
+                      dispdata->surface_w, dispdata->surface_h, surface_fmt, surface_flags);
 
     if (!windata->gs) {
         return SDL_SetError("Could not create GBM surface");
@@ -857,6 +971,7 @@ KMSDRM_VideoQuit(_THIS)
     viddata->video_init = SDL_FALSE;
 }
 
+/* Read modes from the connector modes, and store them in display->display_modes. */
 void
 KMSDRM_GetDisplayModes(_THIS, SDL_VideoDisplay * display)
 {
@@ -905,12 +1020,13 @@ KMSDRM_SetDisplayMode(_THIS, SDL_VideoDisplay * display, SDL_DisplayMode * mode)
         return SDL_SetError("Mode doesn't have an associated index");
     }
 
-    /* Take note of the new mode to be set. */
+    /* Take note of the new mode to be set, and leave the modeset pending. */
     dispdata->mode = conn->modes[modedata->mode_index];
+    dispdata->modeset_pending = SDL_TRUE; 
 
-    /* Take note that we have to change mode in SwapWindow(). We have to do it there
-       because we need a buffer of the new size so the drmModeSetCrtc() call succeeds.  */
-    dispdata->modeset_pending = SDL_TRUE;
+    /* Set the new surface size. */
+    dispdata->surface_w = dispdata->mode.hdisplay; 
+    dispdata->surface_h = dispdata->mode.vdisplay; 
 
     for (i = 0; i < viddata->num_windows; i++) {
         SDL_Window *window = viddata->windows[i];
@@ -1002,62 +1118,58 @@ KMSDRM_CreateWindow(_THIS, SDL_Window * window)
     SDL_bool vulkan_mode = viddata->vulkan_mode; /* Do we have any Vulkan windows? */
     NativeDisplayType egl_display;
     int ret = 0;
+    drmModeModeInfo *mode;
 
     if ( !(dispdata->gbm_init) && !is_vulkan && !vulkan_mode ) {
- 
-         /* If this is not a Vulkan Window, then this is a GL window, so at the
-            end of this function, we must have marked the window as being OPENGL
-            and we must have loaded the GL library: both things are needed so the
-            GL_CreateRenderer() and GL_LoadFunctions() calls in SDL_CreateWindow()
-            succeed without having to re-create the window.
-            We must load the EGL library too, which can't be loaded until the GBM
-            device has been created, because SDL_EGL_Library() function uses it. */ 
-
-         /* Maybe you didn't ask for an OPENGL window, but that's what you will get.
-            See previous comment on why. */
-         window->flags |= SDL_WINDOW_OPENGL;
-
-         /* We need that the fb that SDL gives us has the same size as the videomode
-            currently configure on the CRTC, because the LEGACY interface doesn't
-            support scaling on the primary plane on most hardware (and overlay
-            planes are not present in all hw), so the CRTC reads the PRIMARY PLANE
-            without any scaling, and that's all.
-            So AR-correctin is also impossible on the LEGACY interface. */
-         window->w = dispdata->mode.hdisplay;
-         window->h = dispdata->mode.vdisplay;
-
-         /* Reopen FD, create gbm dev, setup display plane, etc,.
+
+        /* If this is not a Vulkan Window, then this is a GL window, so at the
+	   end of this function, we must have marked the window as being OPENGL
+	   and we must have loaded the GL library: both things are needed so the
+	   GL_CreateRenderer() and GL_LoadFunctions() calls in SDL_CreateWindow()
+	   succeed without having to re-create the window.
+	   We must load the EGL library too, which can't be loaded until the GBM
+	   device has been created, because SDL_EGL_Library() function uses it. */ 
+
+	/* Maybe you didn't ask for an OPENGL window, but that's what you will get.
+	   See previous comment on why. */
+        window->flags |= SDL_WINDOW_OPENGL;
+
+        /* Don't force fullscreen on all windows: it confuses programs that try
+           to set a window fullscreen after creating it as non-fullscreen (sm64ex) */
+        // window->flags |= SDL_WINDOW_FULLSCREEN;
+
+        /* Reopen FD, create gbm dev, setup display plane, etc,.
             but only when we come here for the first time,
             and only if it's not a VK window. */
-         if ((ret = KMSDRM_GBMInit(_this, dispdata))) {
+        if ((ret = KMSDRM_GBMInit(_this, dispdata))) {
                  goto cleanup;
-         }
-
-         /* Manually load the GL library. KMSDRM_EGL_LoadLibrary() has already
-            been called by SDL_CreateWindow() but we don't do anything there,
-            precisely to be able to load it here.
-            If we let SDL_CreateWindow() load the lib, it will be loaded
-            before we call KMSDRM_GBMInit(), causing GLES programs to fail. */
-         if (!_this->egl_data) {
-             egl_display = (NativeDisplayType)((SDL_VideoData *)_this->driverdata)->gbm_dev;
-             if (SDL_EGL_LoadLibrary(_this, NULL, egl_display, EGL_PLATFORM_GBM_MESA)) {
-                 goto cleanup;
-             }
+        }
+
+        /* Manually load the GL library. KMSDRM_EGL_LoadLibrary() has already
+           been called by SDL_CreateWindow() but we don't do anything there,
+           precisely to be able to load it here.
+           If we let SDL_CreateWindow() load the lib, it will be loaded
+           before we call KMSDRM_GBMInit(), causing GLES programs to fail. */
+        if (!_this->egl_data) {
+            egl_display = (NativeDisplayType)((SDL_VideoData *)_this->driverdata)->gbm_dev;
+            if (SDL_EGL_LoadLibrary(_this, NULL, egl_display, EGL_PLATFORM_GBM_MESA)) {
+                goto cleanup;
+            }
 
-             if (SDL_GL_LoadLibrary(NULL) < 0) {
+            if (SDL_GL_LoadLibrary(NULL) < 0) {
                 goto cleanup;
-             }
-         }
+            }
+        }
      
-         /* Can't init mouse stuff sooner because cursor plane is not ready,
-            so we do it here. */
-         KMSDRM_InitMouse(_this);
+	/* Can't init mouse stuff sooner because cursor plane is not ready,
+	   so we do it here. */
+	KMSDRM_InitMouse(_this);
 
-         /* Since we take cursor buffer way from the cursor plane and
-            destroy the cursor GBM BO when we destroy a window, we must
-            also manually re-show the cursor on screen, if necessary,
-            when we create a window. */
-         KMSDRM_InitCursor();
+	/* Since we take cursor buffer way from the cursor plane and
+	   destroy the cursor GBM BO when we destroy a window, we must
+	   also manually re-show the cursor on screen, if necessary,
+	   when we create a window. */
+	KMSDRM_InitCursor();
     }
 
     /* Allocate window internal data */
@@ -1067,31 +1179,37 @@ KMSDRM_CreateWindow(_THIS, SDL_Window * window)
         goto cleanup;
     }
 
-    /* Don't force fullscreen on all windows: it confuses programs that try
-       to set a window fullscreen after creating it as non-fullscreen (sm64ex) */
-    // window->flags |= SDL_WINDOW_FULLSCREEN;
-
     /* Setup driver data for this window */
     windata->viddata = viddata;
     window->driverdata = windata;
 
+    /* We simply IGNORE if it's a fullscreen window, window->flags desn't reflect it.
+       If it's fullscreen, we will manage that in KMSDRM_SetWindwoFullscreen(),
+       which will be called by SDL later, if necessary. */
+    mode = KMSDRM_GetConnectorMode(dispdata->connector, window->w, window->h );
+
     if (!is_vulkan && !vulkan_mode) {
-        /* Create the window surfaces. Needs the window diverdata in place. */
-        if ((ret = KMSDRM_CreateSurfaces(_this, window))) {
-            goto cleanup;
-        }
 
-        /* Configure the current video mode on the CRTC, without changing the buffer
-           it's pointing to (well, that the primary plane connected to the CRTC is
-           pointing to). */
-        ret = KMSDRM_drmModeSetCrtc(viddata->drm_fd, dispdata->crtc->crtc_id,
-            /*fb_info->fb_id*/ -1, 0, 0, &dispdata->connector->connector_id, 1,
-            &dispdata->mode);
+        /* Try to find a matching video mode for the window, with fallback to the
+            original mode if not available, and configure that mode into the CRTC. */
+	if (mode) {
+	    dispdata->surface_w = window->w;
+	    dispdata->surface_h = window->h;
+	    dispdata->mode = *mode;
+	}
+	else {
+	    dispdata->surface_w = dispdata->original_mode.hdisplay;
+	    dispdata->surface_h = dispdata->original_mode.vdisplay;
+	    dispdata->mode = dispdata->original_mode;
+	}
 
-	if (ret) {
-	    SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Could not set CRTC");
+	dispdata->modeset_pending = SDL_TRUE;
+
+        /* Create the window surfaces with the size we have just chosen.
+           Needs the window diverdata in place. */
+        if ((ret = KMSDRM_CreateSurfaces(_this, window))) {
             goto cleanup;
-	}
+        }
     }
 
     /* Add window to the internal list of tracked windows. Note, while it may
@@ -1118,6 +1236,11 @@ KMSDRM_CreateWindow(_THIS, SDL_Window * window)
     SDL_SetMouseFocus(window);
     SDL_SetKeyboardFocus(window);
 
+    /* Tell app about the size we have determined for the window,
+       so SDL pre-scales to that size for us. */
+    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED,
+        dispdata->surface_w, dispdata->surface_h);
+
     /***********************************************************/
     /* Tell SDL that the mouse has entered the window using an */
     /* artificial event: we have no windowing system to tell   */
@@ -1137,19 +1260,57 @@ cleanup:
 }
 
 /*****************************************************************************/
-/* Re-create a window surfaces without destroying the window itself.         */ 
+/* Re-create a window surfaces without destroying the window itself,         */ 
+/* and set a videomode on the CRTC that matches the surfaces size.           */
 /* To be used by SetWindowSize() and SetWindowFullscreen().                  */
 /*****************************************************************************/
-static int
+void
 KMSDRM_ReconfigureWindow( _THIS, SDL_Window * window) {
-    SDL_bool is_vulkan = window->flags & SDL_WINDOW_VULKAN; /* Is this a VK window? */
 
-    if (!is_vulkan) {
-        if (KMSDRM_CreateSurfaces(_this, window)) {
-            return -1;
+    SDL_DisplayData *dispdata = (SDL_DisplayData *) SDL_GetDisplayForWindow(window)->driverdata;
+
+    if ((window->flags & SDL_WINDOW_FULLSCREEN_DESKTOP) ==
+			 SDL_WINDOW_FULLSCREEN_DESKTOP)
+    {
+	/* Update the current mode to the desktop mode,
+	   take note of pending mode configuration to the CRTC,
+	   and recreate the GBM surface with the same size as the size. */
+	dispdata->surface_w = dispdata->original_mode.hdisplay;
+	dispdata->surface_h = dispdata->original_mode.vdisplay;
+	dispdata->mode = dispdata->original_mode;
+    }
+    else
+    {
+	/* Try to find a valid video mode matching the size of the window. */
+	drmModeModeInfo *mode = KMSDRM_GetConnectorMode(dispdata->connector,
+	  window->windowed.w, window->windowed.h );
+
+	if (mode) {
+            /* If matching mode found, recreate the GBM surface with the size
+               of that mode and configure it on the CRTC. */
+	    dispdata->surface_w = window->windowed.w;
+	    dispdata->surface_h = window->windowed.h;
+	    dispdata->mode = *mode;
+	}
+	else {
+            /* If not matching mode found, recreate the GBM surfaces with the
+               size of the mode that was originally configured on the CRTC,
+               and setup that mode on the CRTC. */
+	    dispdata->surface_w = dispdata->original_mode.hdisplay;
+	    dispdata->surface_h = dispdata->original_mode.vdisplay;
+	    dispdata->mode = dispdata->original_mode;
         }
     }
-    return 0;
+
+    /* Recreate the GBM (and EGL) surfaces, and mark the CRTC mode/fb setting
+       as pending so it's done on SwaWindon.  */
+    KMSDRM_CreateSurfaces(_this, window);
+    dispdata->modeset_pending = SDL_TRUE;
+
+    /* Tell app about the size we have determined for the window,
+       so SDL pre-scales to that size for us. */
+    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED,
+    dispdata->surface_w, dispdata->surface_h);
 }
 
 int
@@ -1173,15 +1334,17 @@ KMSDRM_SetWindowPosition(_THIS, SDL_Window * window)
 void
 KMSDRM_SetWindowSize(_THIS, SDL_Window * window)
 {
-    if (KMSDRM_ReconfigureWindow(_this, window)) {
-        SDL_SetError("Can't reconfigure window on SetWindowSize.");
+    SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
+    if (!viddata->vulkan_mode) {
+        KMSDRM_ReconfigureWindow(_this, window);
     }
 }
 void
 KMSDRM_SetWindowFullscreen(_THIS, SDL_Window * window, SDL_VideoDisplay * display, SDL_bool fullscreen)
 {
-    if (KMSDRM_ReconfigureWindow(_this, window)) {
-        SDL_SetError("Can't reconfigure window on SetWindowFullscreen.");
+    SDL_VideoData *viddata = ((SDL_VideoData *)_this->driverdata);
+    if (!viddata->vulkan_mode) {
+        KMSDRM_ReconfigureWindow(_this, window);
     }
 }
 void

src/video/kmsdrm/SDL_kmsdrmvideo.h

@@ -62,6 +62,7 @@ typedef struct SDL_DisplayData
     drmModeCrtc *crtc;
     drmModeModeInfo mode;
     drmModeModeInfo original_mode;
+    drmModeModeInfo next_mode; /* New mode to be set on the CRTC. */
 
     drmModeCrtc *saved_crtc;    /* CRTC to restore on quit */
 
@@ -74,9 +75,11 @@ typedef struct SDL_DisplayData
     struct gbm_bo *cursor_bo;
     uint64_t cursor_w, cursor_h;
 
+    SDL_bool set_default_cursor_pending;
     SDL_bool modeset_pending;
 
-    SDL_bool set_default_cursor_pending;
+    uint32_t surface_w;
+    uint32_t surface_h;
 
 } SDL_DisplayData;
 
@@ -107,6 +110,7 @@ typedef struct KMSDRM_FBInfo
 /* Helper functions */
 int KMSDRM_CreateSurfaces(_THIS, SDL_Window * window);
 KMSDRM_FBInfo *KMSDRM_FBFromBO(_THIS, struct gbm_bo *bo);
+KMSDRM_FBInfo *KMSDRM_FBFromBO2(_THIS, struct gbm_bo *bo, int w, int h);
 SDL_bool KMSDRM_WaitPageFlip(_THIS, SDL_WindowData *windata, int timeout);
 
 /****************************************************************************/