Only fetch language IDs if required

xhcid/src/xhci/scheme.rs

@@ -1444,16 +1444,22 @@ impl Xhci {
         let raw_dd = self.fetch_dev_desc(port_id, slot).await?;
         log::debug!("port {} slot {} desc {:X?}", port_id, slot, raw_dd);
 
-        let lang_ids = self.fetch_lang_ids_desc(port_id, slot).await?;
-        // Prefer US English, but fall back to first language ID, or zero
-        let en_us_id = 0x409;
-        let lang_id = if lang_ids.contains(&en_us_id) {
-            en_us_id
-        } else {
-            match lang_ids.first() {
-                Some(some) => *some,
-                None => 0,
+        // Only fetch language IDs if we need to. Some devices will fail to return this descriptor
+        //TODO: also check configurations and interfaces for defined strings?
+        let lang_id = if raw_dd.manufacturer_str > 0 || raw_dd.product_str > 0 || raw_dd.serial_str > 0 {
+            let lang_ids = self.fetch_lang_ids_desc(port_id, slot).await?;
+            // Prefer US English, but fall back to first language ID, or zero
+            let en_us_id = 0x409;
+            if lang_ids.contains(&en_us_id) {
+                en_us_id
+            } else {
+                match lang_ids.first() {
+                    Some(some) => *some,
+                    None => 0,
+                }
             }
+        } else {
+            0
         };
         log::debug!("port {} using language ID 0x{:04x}", port_id, lang_id);