Do not flush the wrong fifo

embassy-usb-synopsys-otg/CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 <!-- next-header -->
 ## Unreleased - ReleaseDate
 
+- Disabling an OUT endpoint no longer flushes the TX FIFO of the corresponding IN endpoint
+
 ## 0.3.1 - 2025-08-26
 
 - Improve receive performance, more efficient copy from FIFO

embassy-usb-synopsys-otg/src/lib.rs

@@ -945,18 +945,6 @@ impl<'d, const MAX_EP_COUNT: usize> embassy_usb_driver::Bus for Bus<'d, MAX_EP_C
                     regs.doepctl(ep_addr.index()).modify(|w| {
                         w.set_usbaep(enabled);
                     });
-
-                    // Flush tx fifo
-                    regs.grstctl().write(|w| {
-                        w.set_txfflsh(true);
-                        w.set_txfnum(ep_addr.index() as _);
-                    });
-                    loop {
-                        let x = regs.grstctl().read();
-                        if !x.txfflsh() {
-                            break;
-                        }
-                    }
                 });
 
                 // Wake `Endpoint::wait_enabled()`
@@ -975,7 +963,19 @@ impl<'d, const MAX_EP_COUNT: usize> embassy_usb_driver::Bus for Bus<'d, MAX_EP_C
                     regs.diepctl(ep_addr.index()).modify(|w| {
                         w.set_usbaep(enabled);
                         w.set_cnak(enabled); // clear NAK that might've been set by SNAK above.
-                    })
+                    });
+
+                    // Flush tx fifo
+                    regs.grstctl().write(|w| {
+                        w.set_txfflsh(true);
+                        w.set_txfnum(ep_addr.index() as _);
+                    });
+                    loop {
+                        let x = regs.grstctl().read();
+                        if !x.txfflsh() {
+                            break;
+                        }
+                    }
                 });
 
                 // Wake `Endpoint::wait_enabled()`