[Mesa-dev] [PATCH 6/9] i965/gen7: Add the ability to send URB_WRITE_OWORD messages.

[Paul Berry]

Previously, brw_urb_WRITE() would always generate a URB_WRITE_HWORD
message, we always wanted to write data to the URB in pairs of varying
slots or larger (an HWORD is 32 bytes, which is 2 varying slots).

In order to support geometry shader EndPrimitive functionality, we'll
need the ability to write to just a single OWORD (16 byte) slot, since
we'll only be outputting 32 of the control data bits at a time.  So
this patch adds a flag that will cause brw_urb_WRITE to generate a
URB_WRITE_OWORD message.
---
 src/mesa/drivers/dri/i965/brw_defines.h | 3 ++-
 src/mesa/drivers/dri/i965/brw_eu.h      | 8 ++++++++
 src/mesa/drivers/dri/i965/brw_eu_emit.c | 7 ++++++-
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index 6db2570..4742103 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -1172,7 +1172,8 @@ enum brw_message_target {
 #define BRW_MATH_DATA_VECTOR  0
 #define BRW_MATH_DATA_SCALAR  1
 
-#define BRW_URB_OPCODE_WRITE  0
+#define BRW_URB_OPCODE_WRITE_HWORD  0
+#define BRW_URB_OPCODE_WRITE_OWORD  1
 
 #define BRW_URB_SWIZZLE_NONE          0
 #define BRW_URB_SWIZZLE_INTERLEAVE    1
diff --git a/src/mesa/drivers/dri/i965/brw_eu.h b/src/mesa/drivers/dri/i965/brw_eu.h
index 4d47cdd..720bc74 100644
--- a/src/mesa/drivers/dri/i965/brw_eu.h
+++ b/src/mesa/drivers/dri/i965/brw_eu.h
@@ -264,6 +264,14 @@ enum brw_urb_write_flags {
    BRW_URB_WRITE_USE_CHANNEL_MASKS = 0x20,
 
    /**
+    * Indicates that the data should be sent to the URB using the
+    * URB_WRITE_OWORD message rather than URB_WRITE_HWORD (gen == 7).  This
+    * causes offsets to be interpreted as multiples of an OWORD instead of an
+    * HWORD, and only allows one OWORD to be written.
+    */
+   BRW_URB_WRITE_OWORD = 0x40,
+
+   /**
     * Convenient combination of flags: end the thread while simultaneously
     * marking the given URB entry as complete.
     */
diff --git a/src/mesa/drivers/dri/i965/brw_eu_emit.c b/src/mesa/drivers/dri/i965/brw_eu_emit.c
index 0995a9a..9b95101 100644
--- a/src/mesa/drivers/dri/i965/brw_eu_emit.c
+++ b/src/mesa/drivers/dri/i965/brw_eu_emit.c
@@ -527,7 +527,12 @@ static void brw_set_urb_message( struct brw_compile *p,
 			      msg_length, response_length, true,
                               flags & BRW_URB_WRITE_EOT);
    if (brw->gen == 7) {
-      insn->bits3.urb_gen7.opcode = 0;	/* URB_WRITE_HWORD */
+      if (flags & BRW_URB_WRITE_OWORD) {
+         assert(msg_length == 2); /* header + one OWORD of data */
+         insn->bits3.urb_gen7.opcode = BRW_URB_OPCODE_WRITE_OWORD;
+      } else {
+         insn->bits3.urb_gen7.opcode = BRW_URB_OPCODE_WRITE_HWORD;
+      }
       insn->bits3.urb_gen7.offset = offset;
       assert(swizzle_control != BRW_URB_SWIZZLE_TRANSPOSE);
       insn->bits3.urb_gen7.swizzle_control = swizzle_control;
-- 
1.8.4