server udc fix

server/src/usb_gadget.rs

@@ -65,43 +65,40 @@ impl UsbGadget {
         Err(anyhow::anyhow!("⚠️ UDC {ctrl} did not re‑appear within {limit_ms} ms"))
     }
 
+    /// Scan platform devices when /sys/class/udc is empty
+    fn probe_platform_udc() -> Result<Option<String>> {
+        for entry in fs::read_dir("/sys/bus/platform/devices")? {
+            let p = entry?.file_name().into_string().unwrap();
+            if p.ends_with(".usb") { return Ok(Some(p)); }
+        }
+        Ok(None)
+    }
+
     /*–––– public API ––––*/
 
     /// Hard‑reset the gadget → identical to a physical cable re‑plug
     pub fn cycle(&self) -> Result<()> {
         /* 0 – ensure we *know* the controller even after a previous crash */
-        let ctrl = match Self::find_controller() {
+        let mut ctrl = Self::find_controller()
-            Ok(c) => c,
+            .or_else(|_| Self::probe_platform_udc()?
-            Err(_) => {
+                .ok_or_else(|| anyhow::anyhow!("no UDC present")))?;
-                // try to recover by reading the last name from the gadget’s UDC file
-                let last = fs::read_to_string(self.udc_file)?.trim().to_owned();
-                if last.is_empty() {
-                    return Err(anyhow::anyhow!("no UDC present and UDC file is empty"));
-                }
-                warn!("⚠️  UDC missing, attempting to re‑bind {last}");
-                Self::rebind_driver(&last)?;
-                last
-            }
-        };
 
         /* 1 – detach gadget */
         info!("🔌 detaching gadget from {ctrl}");
         Self::write_attr(self.udc_file, "")?;
         Self::wait_state(&ctrl, "not attached", 3_000)?;
 
-        /* 2 – unbind / bind platform driver (dwc2/dwc3) */
+        /* 2 – reset driver */
         Self::rebind_driver(&ctrl)?;
-        Self::wait_udc_present(&ctrl, 3_000)
-            .context("controller did not re‑appear after bind")?;
 
-        /* 3 – re‑attach gadget */
+        /* 3 – wait UDC node to re‑appear */
+        Self::wait_udc_present(&ctrl, 3_000)?;
+
+        /* 4 – re‑attach + pull‑up */
         info!("🔌 re‑attaching gadget to {ctrl}");
         Self::write_attr(self.udc_file, &ctrl)?;
-
-        /* 4 – assert pull‑up */
         let sc = format!("/sys/class/udc/{ctrl}/soft_connect");
-        // toggle 0 → 1 to force the controller to assert pull‑ups
+        Self::write_attr(&sc, "0")?;
-        Self::write_attr(&sc, "0")?;                         // guarantee clean edge
         thread::sleep(Duration::from_millis(50));
         Self::write_attr(&sc, "1")?;
 
@@ -128,20 +125,28 @@ impl UsbGadget {
 
     /// helper: unbind + 300 ms reset + bind
     fn rebind_driver(ctrl: &str) -> Result<()> {
-        let cand = ["dwc2", "dwc3"]; // cover RasPi, RK, AM62, …
+        let cand = ["dwc2", "dwc3"];
         for drv in cand {
             let root = format!("/sys/bus/platform/drivers/{drv}");
-            if !Path::new(&root).exists() {
+            if !Path::new(&root).exists() { continue }
-                continue;
+
-            }
             info!("🔧 unbinding UDC driver ({drv})");
-            Self::write_attr(format!("{root}/unbind"), ctrl)?;
+            let _ = Self::write_attr(format!("{root}/unbind"), ctrl); // ignore EINVAL
-            thread::sleep(Duration::from_millis(500));
+            thread::sleep(Duration::from_millis(300));
 
             info!("🔧 binding   UDC driver ({drv})");
-            Self::write_attr(format!("{root}/bind"), ctrl)?;
+            for attempt in 1..=10 {
-            thread::sleep(Duration::from_millis(500));
+                match Self::write_attr(format!("{root}/bind"), ctrl) {
-            return Ok(());
+                    Ok(_) => return Ok(()),
+                    Err(e) if attempt < 10 => {
+                        trace!("bind busy (#{attempt}) – retrying…");
+                        thread::sleep(Duration::from_millis(100));
+                        continue;
+                    }
+                    Err(e) => return Err(e)
+                        .context(format!("bind failed after {attempt} tries")),
+                }
+            }
         }
         Err(anyhow::anyhow!("no dwc2/dwc3 driver nodes found"))
     }