drm/xe: Split xe_migrate allocation from initialization

Currently, xe_migrate_init handled both allocation and initialization,
Lets moves allocation to xe_tile_alloc via a new xe_migrate_alloc
function, and keep initialization in xe_migrate_init.
This will allow the migration pointers to be passed to other structures
before full initialization.
Also replaces devm_kzalloc with drmm_kzalloc for better
DRM-managed memory.

Signed-off-by: Piotr Piórkowski <[e-mail]>
Reviewed-by: Matthew Brost <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lucas De Marchi <[e-mail]>

drivers/gpu/drm/xe/xe_migrate.c

···
 }
 
 /**
+ * xe_migrate_alloc - Allocate a migrate struct for a given &xe_tile
+ * @tile: &xe_tile
+ *
+ * Allocates a &xe_migrate for a given tile.
+ *
+ * Return: &xe_migrate on success, or NULL when out of memory.
+ */
+struct xe_migrate *xe_migrate_alloc(struct xe_tile *tile)
+{
+	struct xe_migrate *m = drmm_kzalloc(&tile_to_xe(tile)->drm, sizeof(*m), GFP_KERNEL);
+
+	if (m)
+		m->tile = tile;
+	return m;
+}
+
+/**
  * xe_migrate_init() - Initialize a migrate context
  * @tile: Back-pointer to the tile we're initializing for.
  *
···
 {
 	struct xe_device *xe = tile_to_xe(tile);
 	struct xe_gt *primary_gt = tile->primary_gt;
-	struct xe_migrate *m;
+	struct xe_migrate *m = tile->migrate;
 	struct xe_vm *vm;
 	int err;
-
-	m = devm_kzalloc(xe->drm.dev, sizeof(*m), GFP_KERNEL);
-	if (!m)
-		return ERR_PTR(-ENOMEM);
-
-	m->tile = tile;
 
 	/* Special layout, prepared below.. */
 	vm = xe_vm_create(xe, XE_VM_FLAG_MIGRATION |

drivers/gpu/drm/xe/xe_migrate.h

···
 	u8 tile_id;
 };
 
+struct xe_migrate *xe_migrate_alloc(struct xe_tile *tile);
 struct xe_migrate *xe_migrate_init(struct xe_tile *tile);
 
 struct dma_fence *xe_migrate_to_vram(struct xe_migrate *m,

drivers/gpu/drm/xe/xe_tile.c

···
 	if (!tile->mem.ggtt)
 		return -ENOMEM;
 
+	tile->migrate = xe_migrate_alloc(tile);
+	if (!tile->migrate)
+		return -ENOMEM;
+
 	return 0;
 }