Mesa (master): i965: Always try to create a logical context

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: b5e266765a60aa0f05de646d5580ee8c71156ff1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b5e266765a60aa0f05de646d5580ee8c71156ff1

Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Dec 15 13:42:25 2017 +0000

i965: Always try to create a logical context

Always enable use of HW logical contexts to preserve GPU state between
batches when the kernel supports such constructs, continuing to enforce
the required support for gen6+.

At runtime, this effectively removes the BRW_NEW_CONTEXT flag (and the
upload of invariant state) from the start of every batch for any kernel
supporting contexts. So long as the older atoms are correctly listening
to the right flag (NEW_CONTEXT rather than NEW_BATCH) this should
eliminate a few redundant state uploads for the older platforms.

No piglits were harmed on ctg and ilk, both with and without logical
contexts.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/drivers/dri/i965/brw_context.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 01a3e16583..9da7e283ed 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -989,22 +989,21 @@ brwCreateContext(gl_api api,
 
    intel_batchbuffer_init(brw);
 
-   if (devinfo->gen >= 6) {
-      /* Create a new hardware context.  Using a hardware context means that
-       * our GPU state will be saved/restored on context switch, allowing us
-       * to assume that the GPU is in the same state we left it in.
-       *
-       * This is required for transform feedback buffer offsets, query objects,
-       * and also allows us to reduce how much state we have to emit.
-       */
-      brw->hw_ctx = brw_create_hw_context(brw->bufmgr);
-
-      if (!brw->hw_ctx) {
-         fprintf(stderr, "Failed to create hardware context.\n");
-         intelDestroyContext(driContextPriv);
-         return false;
-      }
+   /* Create a new hardware context.  Using a hardware context means that
+    * our GPU state will be saved/restored on context switch, allowing us
+    * to assume that the GPU is in the same state we left it in.
+    *
+    * This is required for transform feedback buffer offsets, query objects,
+    * and also allows us to reduce how much state we have to emit.
+    */
+   brw->hw_ctx = brw_create_hw_context(brw->bufmgr);
+   if (!brw->hw_ctx && devinfo->gen >= 6) {
+      fprintf(stderr, "Failed to create hardware context.\n");
+      intelDestroyContext(driContextPriv);
+      return false;
+   }
 
+   if (brw->hw_ctx) {
       int hw_priority = GEN_CONTEXT_MEDIUM_PRIORITY;
       if (ctx_config->attribute_mask & __DRIVER_CONTEXT_ATTRIB_PRIORITY) {
          switch (ctx_config->priority) {