uvc: send SET_CUR response after data

server/src/bin/lesavka-uvc.rs

@@ -215,7 +215,15 @@ fn main() -> Result<()> {
                             data.length
                         );
                     }
-                    handle_data(&mut state, &mut pending, interfaces, data, debug);
+                    handle_data(
+                        fd,
+                        uvc_send_response,
+                        &mut state,
+                        &mut pending,
+                        interfaces,
+                        data,
+                        debug,
+                    );
                 }
                 _ => {
                     if debug {
@@ -376,9 +384,6 @@ fn handle_setup(
                 return;
             }
             *pending = Some(PendingRequest { interface, selector });
-        let len = req.w_length as usize;
-        let payload = vec![0u8; len.min(UVC_DATA_SIZE)];
-        let _ = send_response(fd, uvc_send_response, &payload);
             if debug {
                 eprintln!(
                     "[lesavka-uvc] SET_CUR queued len={} iface={} sel={}",
@@ -452,6 +457,8 @@ fn maybe_update_ctrl_len(state: &mut UvcState, w_length: u16, debug: bool) {
 }
 
 fn handle_data(
+    fd: i32,
+    uvc_send_response: libc::c_ulong,
     state: &mut UvcState,
     pending: &mut Option<PendingRequest>,
     interfaces: UvcInterfaces,
@@ -507,6 +514,7 @@ fn handle_data(
                 );
             }
         }
+        let _ = send_response(fd, uvc_send_response, &[]);
     }
 }