path: root/0056-egl-wayland-add-EGL_BUFFER_PRESERVED-support.patch

From dbfc536b885044f24207c3180e8d6344c96628fb Mon Sep 17 00:00:00 2001
From: brendan King <Brendan.King@imgtec.com>
Date: Thu, 9 Sep 2021 17:55:13 +0100
Subject: [PATCH] egl/wayland: add EGL_BUFFER_PRESERVED support

When the next back buffer is obtained, and the swap method is
EGL_BUFFER_PRESERVED, the current buffer contents are preserved with
a blit, unless the DRI driver is using the image loader extension,
and the DRI driver requests the current buffer contents
(__DRI_IMAGE_BUFFER_PREV) as well as the back buffer. This allows the
blit to be avoided for GPUs that can support EGL_BUFFER_PRESERVED
directly.

Querying the age of a back buffer may force a blit, but outside of EGL
conformance testing, this would be an odd thing to do, as the buffer
age can always be assumed to be 1 with EGL_BUFFER_PRESERVED.

Any received dmabuf feedback may also force a blit.

The IMG PVR driver does not support the DRI2 loader extension, which
is why the buffer preserved support for the extension is less optimal,
with the current buffer always being preserved with a blit.

EGL_BUFFER_PRESERVED support has not been added for the Mesa software
rasteriser.

---
 include/GL/internal/dri_interface.h     |  4 ++
 src/egl/drivers/dri2/platform_wayland.c | 94 +++++++++++++++++++++----
 2 files changed, 83 insertions(+), 15 deletions(-)

diff --git a/include/GL/internal/dri_interface.h b/include/GL/internal/dri_interface.h
index 123349a..618eba9 100644
--- a/include/GL/internal/dri_interface.h
+++ b/include/GL/internal/dri_interface.h
@@ -2036,12 +2036,16 @@ enum __DRIimageBufferMask {
     * OpenGL ES API and little change to the SurfaceFlinger API.
     */
    __DRI_IMAGE_BUFFER_SHARED = (1 << 2),
+#define DRI_IMAGE_HAS_BUFFER_PREV
+   __DRI_IMAGE_BUFFER_PREV = (1 << 31),
+
 };
 
 struct __DRIimageList {
    uint32_t image_mask;
    __DRIimage *back;
    __DRIimage *front;
+   __DRIimage *prev;
 };
 
 #define __DRI_IMAGE_LOADER "DRI_IMAGE_LOADER"
diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 64c7a42..156a452 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -962,12 +962,22 @@ dri2_wl_swap_interval(_EGLDisplay *disp, _EGLSurface *surf, EGLint interval)
 }
 
 static void
-dri2_wl_release_buffers(struct dri2_egl_surface *dri2_surf)
+dri2_wl_release_buffers(struct dri2_egl_surface *dri2_surf,
+                        bool release_non_current,
+                        bool release_current)
 {
    struct dri2_egl_display *dri2_dpy =
       dri2_egl_display(dri2_surf->base.Resource.Display);
 
    for (int i = 0; i < ARRAY_SIZE(dri2_surf->color_buffers); i++) {
+      if (dri2_surf->current == &dri2_surf->color_buffers[i]) {
+         if (!release_current)
+            continue;
+      } else {
+         if (!release_non_current)
+            continue;
+      }
+
       if (dri2_surf->color_buffers[i].wl_buffer) {
          if (dri2_surf->color_buffers[i].locked) {
             dri2_surf->color_buffers[i].wl_release = true;
@@ -992,6 +1002,9 @@ dri2_wl_release_buffers(struct dri2_egl_surface *dri2_surf)
 
    if (dri2_dpy->dri2)
       dri2_egl_surface_free_local_buffers(dri2_surf);
+
+   if (release_current)
+      dri2_surf->current = NULL;
 }
 
 static void
@@ -1114,7 +1127,8 @@ create_dri_image(struct dri2_egl_surface *dri2_surf,
 }
 
 static int
-get_back_bo(struct dri2_egl_surface *dri2_surf)
+get_back_bo(struct dri2_egl_surface *dri2_surf, bool allow_preserve,
+            bool preserve_current)
 {
    struct dri2_egl_display *dri2_dpy =
       dri2_egl_display(dri2_surf->base.Resource.Display);
@@ -1200,6 +1214,28 @@ get_back_bo(struct dri2_egl_surface *dri2_surf)
           return -1;
    }
 
+   if ((allow_preserve || preserve_current) &&
+       dri2_surf->base.SwapBehavior == EGL_BUFFER_PRESERVED &&
+       dri2_surf->current && dri2_surf->back->age != 1) {
+         _EGLContext *ctx = _eglGetCurrentContext();
+         struct dri2_egl_context *dri2_ctx = dri2_egl_context(ctx);
+
+         if (dri2_ctx) {
+            dri2_dpy->image->blitImage(dri2_ctx->dri_context,
+                                       dri2_surf->back->dri_image,
+                                       dri2_surf->current->dri_image,
+                                       0, 0, dri2_surf->base.Width,
+                                       dri2_surf->base.Height,
+                                       0, 0, dri2_surf->base.Width,
+                                       dri2_surf->base.Height,
+                                       __BLIT_FLAG_FLUSH);
+            dri2_surf->back->age = 1;
+
+	    if (!preserve_current)
+               dri2_surf->current = NULL;
+	 }
+   }
+
    dri2_surf->back->locked = true;
 
    return 0;
@@ -1257,8 +1293,12 @@ front_bo_to_dri_buffer(struct dri2_egl_display *dri2_dpy,
 
 static int
 update_buffers(struct dri2_egl_display *dri2_dpy,
-               struct dri2_egl_surface *dri2_surf)
+               struct dri2_egl_surface *dri2_surf,
+               bool allow_preserve)
 {
+   bool preserve_current = false;
+   int res;
+
    if (dri2_surf->wl_win &&
        (dri2_surf->base.Width != dri2_surf->wl_win->width ||
         dri2_surf->base.Height != dri2_surf->wl_win->height)) {
@@ -1268,12 +1308,20 @@ update_buffers(struct dri2_egl_display *dri2_dpy,
    }
 
    if (dri2_surf->resized || dri2_surf->received_dmabuf_feedback) {
-      dri2_wl_release_buffers(dri2_surf);
+      preserve_current = !dri2_surf->resized &&
+         dri2_surf->base.SwapBehavior == EGL_BUFFER_PRESERVED;
+
+      dri2_wl_release_buffers(dri2_surf, true, !preserve_current);
       dri2_surf->resized = false;
       dri2_surf->received_dmabuf_feedback = false;
    }
 
-   if (get_back_bo(dri2_surf) < 0) {
+   res = get_back_bo(dri2_surf, allow_preserve, preserve_current);
+
+   if (preserve_current)
+         dri2_wl_release_buffers(dri2_surf, false, true);
+
+   if (res < 0) {
       _eglError(EGL_BAD_ALLOC, "failed to allocate color buffer");
       return -1;
    }
@@ -1303,12 +1351,13 @@ update_buffers(struct dri2_egl_display *dri2_dpy,
 
 static int
 update_buffers_if_needed(struct dri2_egl_display *dri2_dpy,
-                         struct dri2_egl_surface *dri2_surf)
+                         struct dri2_egl_surface *dri2_surf,
+                         bool allow_preserve)
 {
    if (dri2_surf->back != NULL)
       return 0;
 
-   return update_buffers(dri2_dpy, dri2_surf);
+   return update_buffers(dri2_dpy, dri2_surf, allow_preserve);
 }
 
 static __DRIbuffer *
@@ -1327,7 +1376,7 @@ dri2_wl_get_buffers_with_format(__DRIdrawable * driDrawable,
 
       switch (attachments[i]) {
       case __DRI_BUFFER_BACK_LEFT:
-         if (update_buffers_if_needed(dri2_dpy, dri2_surf) < 0)
+         if (update_buffers_if_needed(dri2_dpy, dri2_surf, true) < 0)
             return NULL;
 
          back_bo_to_dri_buffer(dri2_dpy, dri2_surf, &dri2_surf->buffers[j]);
@@ -1412,14 +1461,25 @@ image_get_buffers(__DRIdrawable *driDrawable,
    buffers->image_mask = 0;
    buffers->front = NULL;
    buffers->back = NULL;
+   buffers->prev = NULL;
 
    if (buffer_mask & __DRI_IMAGE_BUFFER_BACK)
    {
-      if (update_buffers_if_needed(dri2_dpy, dri2_surf) < 0)
+      bool buffer_prev = buffer_mask & __DRI_IMAGE_BUFFER_PREV;
+
+      if (update_buffers_if_needed(dri2_dpy, dri2_surf, !buffer_prev) < 0)
          return 0;
 
       buffers->image_mask |= __DRI_IMAGE_BUFFER_BACK;
       buffers->back = dri2_surf->back->dri_image;
+
+      if (buffer_prev && dri2_surf->current &&
+          dri2_surf->base.SwapBehavior == EGL_BUFFER_PRESERVED)
+      {
+         buffers->image_mask |= __DRI_IMAGE_BUFFER_PREV;
+         buffers->prev = dri2_surf->current->dri_image;
+         dri2_surf->back->age = 1;
+      }
    }
 
    if (buffer_mask & __DRI_IMAGE_BUFFER_FRONT)
@@ -1689,7 +1749,7 @@ dri2_wl_swap_buffers_with_damage(_EGLDisplay *disp,
 
    /* Make sure we have a back buffer in case we're swapping without ever
     * rendering. */
-   if (update_buffers_if_needed(dri2_dpy, dri2_surf) < 0)
+   if (update_buffers_if_needed(dri2_dpy, dri2_surf, true) < 0)
       return _eglError(EGL_BAD_ALLOC, "dri2_swap_buffers");
 
    if (draw->SwapInterval > 0) {
@@ -1780,7 +1840,7 @@ dri2_wl_query_buffer_age(_EGLDisplay *disp, _EGLSurface *surface)
    if (surface->Type != EGL_WINDOW_BIT)
       return 0;
 
-   if (update_buffers_if_needed(dri2_dpy, dri2_surf) < 0) {
+   if (update_buffers_if_needed(dri2_dpy, dri2_surf, true) < 0) {
       _eglError(EGL_BAD_ALLOC, "dri2_query_buffer_age");
       return -1;
    }
@@ -2157,7 +2217,7 @@ static const __DRIextension *image_loader_extensions[] = {
 };
 
 static EGLBoolean
-dri2_wl_add_configs_for_visuals(_EGLDisplay *disp)
+dri2_wl_add_configs_for_visuals(_EGLDisplay *disp, bool allow_preserve)
 {
    struct dri2_egl_display *dri2_dpy = dri2_egl_display(disp);
    unsigned int format_count[ARRAY_SIZE(dri2_wl_visuals)] = { 0 };
@@ -2178,6 +2238,10 @@ dri2_wl_add_configs_for_visuals(_EGLDisplay *disp)
          if (dri2_wl_visuals[j].wl_drm_format != WL_DRM_FORMAT_YUYV)
             surface_type |= EGL_PBUFFER_BIT;
 
+         if (allow_preserve &&
+             dri2_dpy->image->base.version >= 9 && dri2_dpy->image->blitImage)
+            surface_type |= EGL_SWAP_BEHAVIOR_PRESERVED_BIT;
+
          dri2_conf = dri2_add_config(disp, dri2_dpy->driver_configs[i],
                count + 1, surface_type, NULL, dri2_wl_visuals[j].rgba_shifts, dri2_wl_visuals[j].rgba_sizes);
          if (dri2_conf) {
@@ -2403,7 +2467,7 @@ dri2_initialize_wayland_drm(_EGLDisplay *disp)
       goto cleanup;
    }
 
-   if (!dri2_wl_add_configs_for_visuals(disp)) {
+   if (!dri2_wl_add_configs_for_visuals(disp, true)) {
       _eglError(EGL_NOT_INITIALIZED, "DRI2: failed to add configs");
       goto cleanup;
    }
@@ -2515,7 +2579,7 @@ swrast_update_buffers(struct dri2_egl_surface *dri2_surf)
         dri2_surf->base.Height != dri2_surf->wl_win->height)) {
 
       if (!zink)
-         dri2_wl_release_buffers(dri2_surf);
+         dri2_wl_release_buffers(dri2_surf, true, true);
 
       dri2_surf->base.Width  = dri2_surf->wl_win->width;
       dri2_surf->base.Height = dri2_surf->wl_win->height;
@@ -2962,7 +3026,7 @@ dri2_initialize_wayland_swrast(_EGLDisplay *disp)
 
    dri2_wl_setup_swap_interval(disp);
 
-   if (!dri2_wl_add_configs_for_visuals(disp)) {
+   if (!dri2_wl_add_configs_for_visuals(disp, false)) {
       _eglError(EGL_NOT_INITIALIZED, "DRI2: failed to add configs");
       goto cleanup;
    }