drm/xe: Make MI_FLUSH_DW immediate size more explicit

Despite its name, MI_FLUSH_DW instruction can write an immediate value
of either dword size or qword size, depending on the 'length' field of
the instruction.  Since "length" excludes the first two dwords of the
instruction, a value of 2 in the length field implies a dword write and
a value of 3 implies a qword write.  Even in cases where the flush
instruction's post-sync operation is set to "no write" we're still
expected to size the overall instruction as if we were doing a dword or
qword write (i.e., a length of 1 shouldn't be used on modern platforms).

Rather than baking a size of "1" into the #define and then adding
another unexplained "+ 1" at all the spots where the definition gets
used, lets just create MI_FLUSH_IMM_DW and MI_FLUSH_IMM_QW definitions
that should be OR'd into the instruction header to make it more explicit
what behavior we're requesting.

Bspec: 60229
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20231016163449.1300701-9-matthew.d.roper@intel.comSigned-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/regs/xe_gpu_commands.h

@@ -30,12 +30,15 @@
 #define   MI_LRI_MMIO_REMAP_EN		REG_BIT(17)
 #define   MI_LRI_FORCE_POSTED		(1<<12)
 
-#define MI_FLUSH_DW		MI_INSTR(0x26, 1)
+#define MI_FLUSH_DW		MI_INSTR(0x26, 0)
 #define   MI_FLUSH_DW_STORE_INDEX	(1<<21)
 #define   MI_INVALIDATE_TLB		(1<<18)
 #define   MI_FLUSH_DW_CCS		(1<<16)
 #define   MI_FLUSH_DW_OP_STOREDW	(1<<14)
 #define   MI_FLUSH_DW_USE_GTT		(1<<2)
+#define   MI_FLUSH_LENGTH		GENMASK(5, 0)
+#define   MI_FLUSH_IMM_DW		REG_FIELD_PREP(MI_FLUSH_LENGTH, 2)
+#define   MI_FLUSH_IMM_QW		REG_FIELD_PREP(MI_FLUSH_LENGTH, 3)
 
 #define MI_BATCH_BUFFER_START		MI_INSTR(0x31, 1)
 

drivers/gpu/drm/xe/xe_ring_ops.c

@@ -80,7 +80,7 @@ static int emit_store_imm_ggtt(u32 addr, u32 value, u32 *dw, int i)
 static int emit_flush_imm_ggtt(u32 addr, u32 value, bool invalidate_tlb,
 			       u32 *dw, int i)
 {
-	dw[i++] = (MI_FLUSH_DW + 1) | MI_FLUSH_DW_OP_STOREDW |
+	dw[i++] = MI_FLUSH_DW | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_IMM_DW |
 		(invalidate_tlb ? MI_INVALIDATE_TLB : 0);
 	dw[i++] = addr | MI_FLUSH_DW_USE_GTT;
 	dw[i++] = 0;
@@ -100,9 +100,9 @@ static int emit_bb_start(u64 batch_addr, u32 ppgtt_flag, u32 *dw, int i)
 
 static int emit_flush_invalidate(u32 flag, u32 *dw, int i)
 {
-	dw[i] = MI_FLUSH_DW + 1;
+	dw[i] = MI_FLUSH_DW;
 	dw[i] |= flag;
-	dw[i++] |= MI_INVALIDATE_TLB | MI_FLUSH_DW_OP_STOREDW |
+	dw[i++] |= MI_INVALIDATE_TLB | MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_IMM_DW |
 		MI_FLUSH_DW_STORE_INDEX;
 
 	dw[i++] = LRC_PPHWSP_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT;
@@ -365,8 +365,8 @@ static void emit_migration_job_gen12(struct xe_sched_job *job,
 
 	i = emit_bb_start(job->batch_addr[1], BIT(8), dw, i);
 
-	dw[i++] = (MI_FLUSH_DW | MI_INVALIDATE_TLB | job->migrate_flush_flags |
-		   MI_FLUSH_DW_OP_STOREDW) + 1;
+	dw[i++] = MI_FLUSH_DW | MI_INVALIDATE_TLB | job->migrate_flush_flags |
+		MI_FLUSH_DW_OP_STOREDW | MI_FLUSH_IMM_DW;
 	dw[i++] = xe_lrc_seqno_ggtt_addr(lrc) | MI_FLUSH_DW_USE_GTT;
 	dw[i++] = 0;
 	dw[i++] = seqno; /* value */