wgl: Flush in-between resolving buffer and presenting

Reviewed-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7535>

src/gallium/frontends/wgl/stw_context.c

@@ -446,13 +446,11 @@ stw_make_current(HDC hDrawDC, HDC hReadDC, DHGLRC dhglrc)
          }
       } else {
          if (old_ctx->shared) {
-            struct pipe_fence_handle *fence = NULL;
-            old_ctx->st->flush(old_ctx->st,
-                               ST_FLUSH_FRONT | ST_FLUSH_WAIT, &fence,
-                               NULL, NULL);
-         }
-         else {
-            old_ctx->st->flush(old_ctx->st, ST_FLUSH_FRONT, NULL, NULL, NULL);
+            stw_st_flush(old_ctx->st, old_ctx->current_framebuffer->stfb,
+                         ST_FLUSH_FRONT | ST_FLUSH_WAIT);
+         } else {
+            stw_st_flush(old_ctx->st, old_ctx->current_framebuffer->stfb,
+                         ST_FLUSH_FRONT);
          }
       }
    }

src/gallium/frontends/wgl/stw_framebuffer.c

@@ -665,7 +665,7 @@ DrvSwapBuffers(HDC hdc)
 
       if (ctx->current_framebuffer == fb) {
          /* flush current context */
-         ctx->st->flush(ctx->st, ST_FLUSH_END_OF_FRAME, NULL, NULL, NULL);
+         stw_st_flush(ctx->st, fb->stfb, ST_FLUSH_END_OF_FRAME);
       }
    }
 

src/gallium/frontends/wgl/stw_st.c

@@ -205,6 +205,9 @@ stw_pipe_blit(struct pipe_context *pipe,
 {
    struct pipe_blit_info blit;
 
+   if (!dst || !src)
+      return;
+
    /* From the GL spec, version 4.2, section 4.1.11 (Additional Multisample
     *  Fragment Operations):
     *
@@ -243,6 +246,48 @@ stw_pipe_blit(struct pipe_context *pipe,
    pipe->blit(pipe, &blit);
 }
 
+struct notify_before_flush_cb_args {
+   struct st_context_iface *stctx;
+   struct stw_st_framebuffer *stwfb;
+   unsigned flags;
+};
+
+static void
+notify_before_flush_cb(void* _args)
+{
+   struct notify_before_flush_cb_args *args = (struct notify_before_flush_cb_args *) _args;
+   struct st_context_iface *st = args->stctx;
+   struct pipe_context *pipe = st->pipe;
+
+   if (args->stwfb->stvis.samples > 1) {
+      /* Resolve the MSAA back buffer. */
+      stw_pipe_blit(pipe,
+                    args->stwfb->textures[ST_ATTACHMENT_BACK_LEFT],
+                    args->stwfb->msaa_textures[ST_ATTACHMENT_BACK_LEFT]);
+
+      /* FRONT_LEFT is resolved in flush_frontbuffer. */
+   }
+}
+
+void
+stw_st_flush(struct st_context_iface *stctx,
+             struct st_framebuffer_iface *stfb,
+             unsigned flags)
+{
+   struct stw_st_framebuffer *stwfb = stw_st_framebuffer(stfb);
+   struct notify_before_flush_cb_args args;
+   struct pipe_fence_handle **pfence = NULL;
+   struct pipe_fence_handle *fence = NULL;
+
+   args.stctx = stctx;
+   args.stwfb = stwfb;
+   args.flags = flags;
+
+   if (flags & ST_FLUSH_WAIT)
+      pfence = &fence;
+   stctx->flush(stctx, flags, pfence, notify_before_flush_cb, &args);
+}
+
 /**
  * Present an attachment of the framebuffer.
  */
@@ -257,12 +302,6 @@ stw_st_framebuffer_present_locked(HDC hdc,
 
    assert(stw_own_mutex(&stwfb->fb->mutex));
 
-   if (stwfb->stvis.samples > 1) {
-      stw_pipe_blit(stctx->pipe,
-                    stwfb->textures[statt],
-                    stwfb->msaa_textures[statt]);
-   }
-
    resource = stwfb->textures[statt];
    if (resource) {
       stw_framebuffer_present_locked(hdc, stwfb->fb, resource);
@@ -282,11 +321,22 @@ stw_st_framebuffer_flush_front(struct st_context_iface *stctx,
                                enum st_attachment_type statt)
 {
    struct stw_st_framebuffer *stwfb = stw_st_framebuffer(stfb);
+   struct pipe_context *pipe = stctx->pipe;
    bool ret;
    HDC hDC;
 
+   if (statt != ST_ATTACHMENT_FRONT_LEFT)
+      return false;
+
    stw_framebuffer_lock(stwfb->fb);
 
+   if (stwfb->stvis.samples > 1) {
+      /* Resolve the front buffer. */
+      stw_pipe_blit(pipe, stwfb->textures[statt], stwfb->msaa_textures[statt]);
+   }
+
+   pipe->flush(pipe, NULL, 0);
+
    /* We must not cache HDCs anywhere, as they can be invalidated by the
     * application, or screen resolution changes. */
 

src/gallium/frontends/wgl/stw_st.h

@@ -46,6 +46,10 @@ stw_st_create_framebuffer(struct stw_framebuffer *fb);
 void
 stw_st_destroy_framebuffer_locked(struct st_framebuffer_iface *stfb);
 
+void
+stw_st_flush(struct st_context_iface *st, struct st_framebuffer_iface *stfb,
+             unsigned flags);
+
 bool
 stw_st_swap_framebuffer_locked(HDC hdc, struct st_context_iface *stctx,
                                struct st_framebuffer_iface *stfb);