i965/gen7: Use the updated interface for SO write pointer resetting.

The new kernel patch I submitted makes the interface opt-in, so all
batchbuffers aren't preceded by the 4 MI_LOAD_REGISTER_IMMs.  This
requires the updated i915_drm.h present in libdrm 2.4.30.

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

configure.ac

@@ -25,7 +25,7 @@ USER_CXXFLAGS="$CXXFLAGS"
 dnl Versions for external dependencies
 LIBDRM_REQUIRED=2.4.24
 LIBDRM_RADEON_REQUIRED=2.4.24
-LIBDRM_INTEL_REQUIRED=2.4.27
+LIBDRM_INTEL_REQUIRED=2.4.30
 LIBDRM_NOUVEAU_REQUIRED=0.6
 DRI2PROTO_REQUIRED=2.6
 GLPROTO_REQUIRED=1.4.14

src/mesa/drivers/dri/i965/gen7_sol_state.c

@@ -240,6 +240,8 @@ upload_sol_state(struct brw_context *brw)
    if (active) {
       upload_3dstate_so_buffers(brw);
       upload_3dstate_so_decl_list(brw, &vue_map);
+
+      intel->batch.needs_sol_reset = true;
    }
 
    /* Finally, set up the SOL stage.  This command must always follow updates to

src/mesa/drivers/dri/intel/intel_batchbuffer.c

@@ -85,6 +85,7 @@ intel_batchbuffer_reset(struct intel_context *intel)
    intel->batch.reserved_space = BATCH_RESERVED;
    intel->batch.state_batch_offset = intel->batch.bo->size;
    intel->batch.used = 0;
+   intel->batch.needs_sol_reset = false;
 }
 
 void
@@ -135,16 +136,20 @@ do_flush_locked(struct intel_context *intel)
    }
 
    if (!intel->intelScreen->no_hw) {
-      int ring;
+      int flags;
 
       if (intel->gen < 6 || !batch->is_blit) {
-	 ring = I915_EXEC_RENDER;
+	 flags = I915_EXEC_RENDER;
       } else {
-	 ring = I915_EXEC_BLT;
+	 flags = I915_EXEC_BLT;
       }
 
+      if (batch->needs_sol_reset)
+	 flags |= I915_EXEC_GEN7_SOL_RESET;
+
       if (ret == 0)
-	 ret = drm_intel_bo_mrb_exec(batch->bo, 4*batch->used, NULL, 0, 0, ring);
+	 ret = drm_intel_bo_mrb_exec(batch->bo, 4*batch->used, NULL, 0, 0,
+				     flags);
    }
 
    if (unlikely(INTEL_DEBUG & DEBUG_BATCH)) {

src/mesa/drivers/dri/intel/intel_context.h

@@ -233,6 +233,7 @@ struct intel_context
 
       uint32_t state_batch_offset;
       bool is_blit;
+      bool needs_sol_reset;
 
       struct {
 	 uint16_t used;