Short-circuit out of NAK on interrupt pipes.

Don't bother retrying. NAK on an interrupt endpoint means there's no
data.

1 files changed, 9 insertions, 2 deletions

diff --git a/usbh/src/pipe.rs b/usbh/src/pipe.rs
index abdba2a..80ebe11 100644
--- a/usbh/src/pipe.rs
+++ b/usbh/src/pipe.rs
@@ -321,9 +321,9 @@ impl Pipe<'_, '_> {
             ep.out_toggle,
         );
         if self.regs.status.read().dtgl().bit_is_set() {
-            self.dtgl_clear();
-        } else {
             self.dtgl_set();
+        } else {
+            self.dtgl_clear();
         }
         if token == PToken::In {
             ep.in_toggle = self.regs.status.read().dtgl().bit_is_set()
@@ -377,6 +377,13 @@ impl Pipe<'_, '_> {
                     last_err = e;
                     match last_err {
                         PipeErr::DataToggle => self.dtgl(ep, token),
+
+                        // Flow error on interrupt pipes means we got
+                        // a NAK, which in this context means there's
+                        // no data. cf §32.8.7.5 of SAM D21 data
+                        // sheet.
+                        PipeErr::Flow if ep.transfer_type == TransferType::Interrupt => break,
+
                         PipeErr::Stall => break,
                         _ => {
                             naks += 1;