From 2745e0b973bf4f2982ff3216be2e45d1e9bd4b4c Mon Sep 17 00:00:00 2001
From: Solomon Peachy <pizza@shaftnet.org>
Date: Sun, 27 Sep 2026 19:01:35 -0400
Subject: [PATCH] FS#14011:  Handle usb hosts whose first request is
 SET_ADDRESS (Anthony Fletcher)

Thanks for the SET_ADDRESS rework. I think it leaves one case uncovered:
a host whose first request is SET_ADDRESS ends up with a device whose
interfaces are all numbered 0.

Two things still depend on the core seeing a request before the address arrives:

  1. usb_core assigns interfaces and endpoints only on the first control
     request it handles in DEFAULT. When SET_ADDRESS comes first, the driver
     completes it and usb_core_set_address() moves the state to ADDRESS. So
     allocate_interfaces_and_endpoints() never runs.
  2. Under USB_DETECT_BY_REQUEST, usb.c enables the class drivers only
     on a USB_TRANSFER_COMPLETION event. The SET_ADDRESS status stage now
     completes inside the driver, so the drivers are still disabled when the
     address arrives.

Change-Id: Ifacb8b07cbdefb0dee3d414c2257a50a08759f3d
---
 firmware/usb.c               |  9 +++++++++
 firmware/usbstack/usb_core.c | 22 +++++++++++++++-------
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/firmware/usb.c b/firmware/usb.c
index 3b73f8ec34..b5b556516c 100644
--- a/firmware/usb.c
+++ b/firmware/usb.c
@@ -431,6 +431,15 @@ static void NORETURN_ATTR usb_thread(void)
 
 #ifdef HAVE_USBSTACK
         case USB_NOTIFY_SET_ADDR:
+#ifdef USB_DETECT_BY_REQUEST
+            /* first sign of a host that addresses before anything else;
+             * the class drivers must be on before interfaces are assigned */
+            if(usb_state > USB_EXTRACTED) {
+                usb_state = USB_INSERTED;
+                usb_set_host_present(true);
+            }
+#endif
+            /* intentional fallthrough */
         case USB_NOTIFY_SET_CONFIG:
         case USB_NOTIFY_BUS_RESET:
         case USB_NOTIFY_CLASS_DRIVER:
diff --git a/firmware/usbstack/usb_core.c b/firmware/usbstack/usb_core.c
index acccee21d2..78becb0fc4 100644
--- a/firmware/usbstack/usb_core.c
+++ b/firmware/usbstack/usb_core.c
@@ -863,9 +863,22 @@ static void request_handler_device_get_descriptor(struct usb_ctrlrequest* req, u
     }
 }
 
+static void usb_core_init_interfaces(void)
+{
+    if(usb_state == DEFAULT) {
+        set_serial_descriptor();
+        usb_core_set_serial_function_id();
+        allocate_interfaces_and_endpoints();
+    }
+}
+
 static void usb_core_set_address(uint8_t address)
 {
     logf("usb_core: SET_ADR %d", address);
+    /* A host may address the device before making any other request;
+      * the driver answers SET_ADDRESS itself, so nothing has been
+      * allocated yet. */
+    usb_core_init_interfaces();
     usb_address = address;
     usb_state = ADDRESS;
 }
@@ -1134,12 +1147,7 @@ static void usb_core_control_request_handler(struct usb_ctrlrequest* req, uint8_
         usb_charging_maxcurrent_change(usb_charging_maxcurrent());
     }
 #endif
-    if(usb_state == DEFAULT) {
-        set_serial_descriptor();
-        usb_core_set_serial_function_id();
-
-        allocate_interfaces_and_endpoints();
-    }
+    usb_core_init_interfaces();
 
     switch(req->bRequestType & USB_RECIP_MASK) {
         case USB_RECIP_DEVICE:
@@ -1251,7 +1259,7 @@ void usb_core_transfer_complete(int ep, int dir, int status, int length) {
 
     /* Control packet handling */
     switch(dir | ep0_state) {
-    /* EXPECT_TX_DATA_STATUS_COMP -(status comp)-> EXPECT_TX_DATA_COMP -(data comp)-> READY 
+    /* EXPECT_TX_DATA_STATUS_COMP -(status comp)-> EXPECT_TX_DATA_COMP -(data comp)-> READY
      *                            -(data comp)-> EXPECT_TX_STATUS_COMP -(status comp)-> READY */
     case USB_DIR_OUT | EP0_EXPECT_TX_DATA_STATUS_COMP:
         logf("usb_core: control-in done success=%d", status == 0 && length == 0);