rp usb: wait for accept() completion

This ensures that the current response has finished being sent
before the subsequent set_address() happens. Otherwise connecting
a device is intermittent, can fail depending on timing.

1 files changed, 13 insertions, 1 deletions

diff --git a/embassy-rp/src/usb.rs b/embassy-rp/src/usb.rs
index 0a904aab3..7a83dcb4a 100644
--- a/embassy-rp/src/usb.rs
+++ b/embassy-rp/src/usb.rs
@@ -811,8 +811,8 @@ impl<'d, T: Instance> driver::ControlPipe for ControlPipe<'d, T> {
         async move {
             trace!("control: accept");
 
+            let bufcontrol = T::dpram().ep_in_buffer_control(0);
             unsafe {
-                let bufcontrol = T::dpram().ep_in_buffer_control(0);
                 bufcontrol.write(|w| {
                     w.set_length(0, 0);
                     w.set_pid(0, true);
@@ -826,6 +826,18 @@ impl<'d, T: Instance> driver::ControlPipe for ControlPipe<'d, T> {
                     w.set_available(0, true);
                 });
             }
+
+            // wait for completion before returning, needed so
+            // set_address() doesn't happen early.
+            poll_fn(|cx| {
+                EP_IN_WAKERS[0].register(cx.waker());
+                if unsafe { bufcontrol.read().available(0) } {
+                    Poll::Pending
+                } else {
+                    Poll::Ready(())
+                }
+            })
+            .await;
         }
     }