[LL][USB] Fix received data length counting when DMA is enabled

Inc/stm32f1xx_ll_usb.h

diff --git a/Inc/stm32f1xx_ll_usb.h b/Inc/stm32f1xx_ll_usb.h
index 68cf834..eb52ac8 100644
--- a/Inc/stm32f1xx_ll_usb.h
+++ b/Inc/stm32f1xx_ll_usb.h
@@ -151,6 +151,8 @@
 
   uint32_t  xfer_len;             /*!< Current transfer length                                                  */
 
+  uint32_t  xfer_size;            /*!< requested transfer size                                                  */
+
   uint32_t  xfer_count;           /*!< Partial transfer length in case of multi packet transfer                 */
 } USB_OTG_EPTypeDef;
 

Src/stm32f1xx_ll_usb.c

diff --git a/Src/stm32f1xx_ll_usb.c b/Src/stm32f1xx_ll_usb.c
index eaae95f..d5544a7 100644
--- a/Src/stm32f1xx_ll_usb.c
+++ b/Src/stm32f1xx_ll_usb.c
@@ -704,8 +704,10 @@
     else
     {
       pktcnt = (uint16_t)((ep->xfer_len + ep->maxpacket - 1U) / ep->maxpacket);
+      ep->xfer_size = ep->maxpacket * pktcnt;
+
       USBx_OUTEP(epnum)->DOEPTSIZ |= USB_OTG_DOEPTSIZ_PKTCNT & ((uint32_t)pktcnt << 19);
-      USBx_OUTEP(epnum)->DOEPTSIZ |= USB_OTG_DOEPTSIZ_XFRSIZ & (ep->maxpacket * pktcnt);
+      USBx_OUTEP(epnum)->DOEPTSIZ |= USB_OTG_DOEPTSIZ_XFRSIZ & ep->xfer_size;
     }
 
     if (ep->type == EP_TYPE_ISOC)
@@ -788,8 +790,11 @@
       ep->xfer_len = ep->maxpacket;
     }
 
+    /* Store transfer size, for EP0 this is equal to endpoint max packet size */
+    ep->xfer_size = ep->maxpacket;
+
     USBx_OUTEP(epnum)->DOEPTSIZ |= (USB_OTG_DOEPTSIZ_PKTCNT & (1U << 19));
-    USBx_OUTEP(epnum)->DOEPTSIZ |= (USB_OTG_DOEPTSIZ_XFRSIZ & (ep->maxpacket));
+    USBx_OUTEP(epnum)->DOEPTSIZ |= (USB_OTG_DOEPTSIZ_XFRSIZ & ep->xfer_size);
 
     /* EP enable */
     USBx_OUTEP(epnum)->DOEPCTL |= (USB_OTG_DOEPCTL_CNAK | USB_OTG_DOEPCTL_EPENA);