cxl/pci: Moving code in cxl_hdm_decode_init()

Commit 3f9e075 ("cxl/pci: simplify the check of mem_enabled in
cxl_hdm_decode_init()") changed the code flow in this function. The
root port is determined before a check to leave the function. Since
the root port is not used by the check it can be moved to run the
check first. This improves code readability and avoids unnesessary
code execution.

Signed-off-by: Robert Richter <[email protected]>
Reviewed-by: Gregory Price <[email protected]>
Reviewed-by: Davidlohr Bueso <[email protected]>
Reviewed-by: Alison Schofield <[email protected]>
Reviewed-by: "Fabio M. De Francesco" <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Tested-by: Gregory Price <[email protected]>
Acked-by: Dan Williams <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Dave Jiang <[email protected]>

Author: Robert Richter

drivers/cxl/core/pci.c

@@ -419,14 +419,6 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
 	if (!hdm)
 		return -ENODEV;
 
-	root = to_cxl_port(port->dev.parent);
-	while (!is_cxl_root(root) && is_cxl_port(root->dev.parent))
-		root = to_cxl_port(root->dev.parent);
-	if (!is_cxl_root(root)) {
-		dev_err(dev, "Failed to acquire root port for HDM enable\n");
-		return -ENODEV;
-	}
-
 	if (!info->mem_enabled) {
 		rc = devm_cxl_enable_hdm(&port->dev, cxlhdm);
 		if (rc)
@@ -435,6 +427,14 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
 		return devm_cxl_enable_mem(&port->dev, cxlds);
 	}
 
+	root = to_cxl_port(port->dev.parent);
+	while (!is_cxl_root(root) && is_cxl_port(root->dev.parent))
+		root = to_cxl_port(root->dev.parent);
+	if (!is_cxl_root(root)) {
+		dev_err(dev, "Failed to acquire root port for HDM enable\n");
+		return -ENODEV;
+	}
+
 	for (i = 0, allowed = 0; i < info->ranges; i++) {
 		struct device *cxld_dev;