[Mesa-dev] [PATCH] intel: Fix initial MakeCurrent for single-buffer drawables

[Kristian Høgsberg]

Commit 05da4a7a5e7d5bd988cb31f94ed8e1f053d9ee39 attempts to eliminate the
call to intel_update_renderbuffer() in the case where we already have a
drawbuffer for the drawable.  Unfortunately this only checks the
back left renderbuffer, which breaks in case of single buffer drawables.

This means that the initial viewport will not be set in that case.  Instead,
we now check whether the initial viewport has not been set and the
drawable size is 0x0, in which case we call out to intel_update_renderbuffer().
This gives us the correct behaviour but also further eliminates a
call to intel_update_renderbuffer() in the case where we make a newly
created drawable current with a context that already has an initial viewport.

https://bugs.freedesktop.org/show_bug.cgi?id=73862

Signed-off-by: Kristian Høgsberg <krh at bitplanet.net>
---
 src/mesa/drivers/dri/i965/brw_context.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index d6c41e6..9183dda 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -917,7 +917,6 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
    if (driContextPriv) {
       struct gl_context *ctx = &brw->ctx;
       struct gl_framebuffer *fb, *readFb;
-      struct intel_renderbuffer *rb = NULL;
 
       if (driDrawPriv == NULL && driReadPriv == NULL) {
          fb = _mesa_get_incomplete_framebuffer();
@@ -925,7 +924,6 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
       } else {
          fb = driDrawPriv->driverPrivate;
          readFb = driReadPriv->driverPrivate;
-         rb = intel_get_renderbuffer(fb, BUFFER_BACK_LEFT);
          driContextPriv->dri2.draw_stamp = driDrawPriv->dri2.stamp - 1;
          driContextPriv->dri2.read_stamp = driReadPriv->dri2.stamp - 1;
       }
@@ -937,11 +935,11 @@ intelMakeCurrent(__DRIcontext * driContextPriv,
       intel_gles3_srgb_workaround(brw, fb);
       intel_gles3_srgb_workaround(brw, readFb);
 
-      if (rb && !rb->mt) {
-         /* If we don't have buffers for the drawable yet, force a call to
-          * getbuffers here so we can have a default drawable size. */
+      /* If the context viewport hasn't been initialized, force a call out to
+       * the loader to get buffers so we have a drawable size for the initial
+       * viewport. */
+      if (!brw->ctx.ViewportInitialized && fb->Width == 0 && fb->Height == 0)
          intel_prepare_render(brw);
-      }
 
       _mesa_make_current(ctx, fb, readFb);
    } else {
-- 
1.8.4.2