usb: device_next: respect bMaxPacketSize0 in control transfers

Only the device operating at high speed has bMaxPacketSize0 set to 64
bytes, the device operating at other speeds may have a different value.
For full speed, use the value from the full speed descriptor.

Signed-off-by: Johann Fischer <[email protected]>

Author: jfischer-no

subsys/usb/device_next/usbd_endpoint.c

@@ -59,7 +59,20 @@ static void usbd_ep_ctrl_set_zlp(struct usbd_context *const uds_ctx,
 				 struct net_buf *const buf)
 {
 	struct usb_setup_packet *setup = usbd_get_setup_pkt(uds_ctx);
+	struct usb_device_descriptor *desc = uds_ctx->fs_desc;
 	size_t min_len = MIN(setup->wLength, buf->len);
+	uint8_t mps0 = 0;
+
+	switch (usbd_bus_speed(uds_ctx)) {
+	case USBD_SPEED_FS:
+		mps0 = desc->bMaxPacketSize0;
+		break;
+	case USBD_SPEED_HS:
+		mps0 = USB_CONTROL_EP_MPS;
+		break;
+	default:
+		__ASSERT(false, "Cannot determine bMaxPacketSize0 (unsupported speed)");
+	}
 
 	if (buf->len == 0) {
 		return;
@@ -70,7 +83,7 @@ static void usbd_ep_ctrl_set_zlp(struct usbd_context *const uds_ctx,
 	 * last chunk is wMaxPacketSize long, to indicate the last
 	 * packet.
 	 */
-	if (setup->wLength > min_len && !(min_len % USB_CONTROL_EP_MPS)) {
+	if (setup->wLength > min_len && !(min_len % mps0)) {
 		/*
 		 * Transfer length is less as requested by wLength and
 		 * is multiple of wMaxPacketSize.