[Mesa-dev] [PATCH 4/8] i965: Emit invariant state once at startup on Gen6+.

[Kenneth Graunke]

Now that we have hardware contexts, we can safely initialize our GPU
state once at startup, rather than needing a state atom with the
BRW_NEW_CONTEXT flag set.

This removes a tiny bit of code from our drawing loop.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_misc_state.c   |  5 +++--
 src/mesa/drivers/dri/i965/brw_state.h        |  1 +
 src/mesa/drivers/dri/i965/brw_state_upload.c | 18 ++++++++++++++++--
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_misc_state.c b/src/mesa/drivers/dri/i965/brw_misc_state.c
index 8162eeb..7e41c84 100644
--- a/src/mesa/drivers/dri/i965/brw_misc_state.c
+++ b/src/mesa/drivers/dri/i965/brw_misc_state.c
@@ -978,7 +978,8 @@ const struct brw_tracked_state brw_line_stipple = {
  * Misc invariant state packets
  */
 
-static void upload_invariant_state( struct brw_context *brw )
+void
+brw_upload_invariant_state(struct brw_context *brw)
 {
    struct intel_context *intel = &brw->intel;
 
@@ -1016,7 +1017,7 @@ const struct brw_tracked_state brw_invariant_state = {
       .brw = BRW_NEW_CONTEXT,
       .cache = 0
    },
-   .emit = upload_invariant_state
+   .emit = brw_upload_invariant_state
 };
 
 /**
diff --git a/src/mesa/drivers/dri/i965/brw_state.h b/src/mesa/drivers/dri/i965/brw_state.h
index 9afc6bb..7215128 100644
--- a/src/mesa/drivers/dri/i965/brw_state.h
+++ b/src/mesa/drivers/dri/i965/brw_state.h
@@ -125,6 +125,7 @@ extern const struct brw_tracked_state gen7_wm_state;
 extern const struct brw_tracked_state haswell_cut_index;
 
 /* brw_misc_state.c */
+void brw_upload_invariant_state(struct brw_context *brw);
 uint32_t
 brw_depthbuffer_format(struct brw_context *brw);
 
diff --git a/src/mesa/drivers/dri/i965/brw_state_upload.c b/src/mesa/drivers/dri/i965/brw_state_upload.c
index 07c49ff..6a69a67 100644
--- a/src/mesa/drivers/dri/i965/brw_state_upload.c
+++ b/src/mesa/drivers/dri/i965/brw_state_upload.c
@@ -111,7 +111,6 @@ static const struct brw_tracked_state *gen6_atoms[] =
    &gen6_sf_vp,
 
    /* Command packets: */
-   &brw_invariant_state,
 
    /* must do before binding table pointers, cc state ptrs */
    &brw_state_base_address,
@@ -177,7 +176,6 @@ static const struct brw_tracked_state *gen7_atoms[] =
    &brw_wm_prog,
 
    /* Command packets: */
-   &brw_invariant_state,
    &gen7_push_constant_alloc,
 
    /* must do before binding table pointers, cc state ptrs */
@@ -241,6 +239,20 @@ static const struct brw_tracked_state *gen7_atoms[] =
    &haswell_cut_index,
 };
 
+static void
+brw_upload_initial_gpu_state(struct brw_context *brw)
+{
+   struct intel_context *intel = &brw->intel;
+
+   /* On platforms with hardware contexts, we can set our initial GPU state
+    * right away rather than doing it via state atoms.  This saves a small
+    * amount of overhead on every draw call.
+    */
+   if (!intel->hw_ctx)
+      return;
+
+   brw_upload_invariant_state(brw);
+}
 
 void brw_init_state( struct brw_context *brw )
 {
@@ -270,6 +282,8 @@ void brw_init_state( struct brw_context *brw )
       assert((*atoms)->emit);
       atoms++;
    }
+
+   brw_upload_initial_gpu_state(brw);
 }
 
 
-- 
1.8.3