i965: Fix up VS max_threads for G4X and removing a magic number.

As far as I can read in the docs, VS threads can be 1:1 with the pairs of
VUE handles allocated for them.  Also, G4X can run twice as many threads as
before (though we won't unless the we bump the preferred URB entries for VS).

1 files changed, 14 insertions, 2 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vs_state.c b/src/mesa/drivers/dri/i965/brw_vs_state.c
index 6e66f54524b..942581696d8 100644
--- a/src/mesa/drivers/dri/i965/brw_vs_state.c
+++ b/src/mesa/drivers/dri/i965/brw_vs_state.c
@@ -77,12 +77,19 @@ vs_unit_create_from_key(struct brw_context *brw, struct brw_vs_unit_key *key)
 {
    struct brw_vs_unit_state vs;
    dri_bo *bo;
+   int chipset_max_threads;
 
    memset(&vs, 0, sizeof(vs));
 
    vs.thread0.kernel_start_pointer = brw->vs.prog_bo->offset >> 6; /* reloc */
    vs.thread0.grf_reg_count = ALIGN(key->total_grf, 16) / 16 - 1;
    vs.thread1.floating_point_mode = BRW_FLOATING_POINT_NON_IEEE_754;
+   /* Choosing multiple program flow means that we may get 2-vertex threads,
+    * which will have the channel mask for dwords 4-7 enabled in the thread,
+    * and those dwords will be written to the second URB handle when we
+    * brw_urb_WRITE() results.
+    */
+   vs.thread1.single_program_flow = 0;
    vs.thread3.urb_entry_read_length = key->urb_entry_read_length;
    vs.thread3.const_urb_entry_read_length = key->curb_entry_read_length;
    vs.thread3.dispatch_grf_start_reg = 1;
@@ -91,8 +98,13 @@ vs_unit_create_from_key(struct brw_context *brw, struct brw_vs_unit_key *key)
 
    vs.thread4.nr_urb_entries = key->nr_urb_entries;
    vs.thread4.urb_entry_allocation_size = key->urb_size - 1;
-   vs.thread4.max_threads = MIN2(MAX2(0, (key->nr_urb_entries - 6) / 2 - 1),
-				 15);
+
+   if (BRW_IS_G4X(brw))
+      chipset_max_threads = 32;
+   else
+      chipset_max_threads = 16;
+   vs.thread4.max_threads = CLAMP(key->nr_urb_entries / 2,
+				  1, chipset_max_threads) - 1;
 
    if (INTEL_DEBUG & DEBUG_SINGLE_THREAD)
       vs.thread4.max_threads = 0;