drm/i915/gt: Optimize the migration and clear loop

Move the static calculations out of the loops for copy and clear.

v2:
  Fix the loss of proper error code on emit_pte
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405150840.29351-4-ramalingam.c@intel.com

drivers/gpu/drm/i915/gt/intel_migrate.c

@@ -526,6 +526,7 @@ intel_context_migrate_copy(struct intel_context *ce,
 			   struct i915_request **out)
 {
 	struct sgt_dma it_src = sg_sgt(src), it_dst = sg_sgt(dst);
+	u32 src_offset, dst_offset;
 	struct i915_request *rq;
 	int err;
 
@@ -535,8 +536,18 @@ intel_context_migrate_copy(struct intel_context *ce,
 
 	GEM_BUG_ON(ce->ring->size < SZ_64K);
 
+	src_offset = 0;
+	dst_offset = CHUNK_SZ;
+	if (HAS_64K_PAGES(ce->engine->i915)) {
+		src_offset = 0;
+		dst_offset = 0;
+		if (src_is_lmem)
+			src_offset = CHUNK_SZ;
+		if (dst_is_lmem)
+			dst_offset = 2 * CHUNK_SZ;
+	}
+
 	do {
-		u32 src_offset, dst_offset;
 		int len;
 
 		rq = i915_request_create(ce);
@@ -564,17 +575,6 @@ intel_context_migrate_copy(struct intel_context *ce,
 		if (err)
 			goto out_rq;
 
-		src_offset = 0;
-		dst_offset = CHUNK_SZ;
-		if (HAS_64K_PAGES(ce->engine->i915)) {
-			src_offset = 0;
-			dst_offset = 0;
-			if (src_is_lmem)
-				src_offset = CHUNK_SZ;
-			if (dst_is_lmem)
-				dst_offset = 2 * CHUNK_SZ;
-		}
-
 		len = emit_pte(rq, &it_src, src_cache_level, src_is_lmem,
 			       src_offset, CHUNK_SZ);
 		if (len <= 0) {
@@ -690,6 +690,7 @@ intel_context_migrate_clear(struct intel_context *ce,
 {
 	struct sgt_dma it = sg_sgt(sg);
 	struct i915_request *rq;
+	u32 offset;
 	int err;
 
 	GEM_BUG_ON(ce->vm != ce->engine->gt->migrate.context->vm);
@@ -697,8 +698,11 @@ intel_context_migrate_clear(struct intel_context *ce,
 
 	GEM_BUG_ON(ce->ring->size < SZ_64K);
 
+	offset = 0;
+	if (HAS_64K_PAGES(ce->engine->i915) && is_lmem)
+		offset = CHUNK_SZ;
+
 	do {
-		u32 offset;
 		int len;
 
 		rq = i915_request_create(ce);
@@ -726,10 +730,6 @@ intel_context_migrate_clear(struct intel_context *ce,
 		if (err)
 			goto out_rq;
 
-		offset = 0;
-		if (HAS_64K_PAGES(ce->engine->i915) && is_lmem)
-			offset = CHUNK_SZ;
-
 		len = emit_pte(rq, &it, cache_level, is_lmem, offset, CHUNK_SZ);
 		if (len <= 0) {
 			err = len;