wait for tx slots before clearing nak

board/drivers/can.h

@@ -28,6 +28,7 @@ void can_set_forwarding(int from, int to);
 
 void can_init(uint8_t can_number);
 void can_init_all(void);
+bool can_tx_check_min_slots_free(int min);
 void can_send(CAN_FIFOMailBox_TypeDef *to_push, uint8_t bus_number, bool skip_tx_hook);
 bool can_pop(can_ring *q, CAN_FIFOMailBox_TypeDef *elem);
 
@@ -107,6 +108,20 @@ bool can_push(can_ring *q, CAN_FIFOMailBox_TypeDef *elem) {
   return ret;
 }
 
+int can_slots_empty(can_ring *q) {
+  int ret = 0;
+
+  ENTER_CRITICAL();
+  if (q->w_ptr >= q->r_ptr) {
+    ret = q->fifo_size - 1 - q->w_ptr + q->r_ptr;
+  } else {
+    ret = q->r_ptr - q->w_ptr - 1;
+  }
+  EXIT_CRITICAL();
+
+  return ret;
+}
+
 void can_clear(can_ring *q) {
   ENTER_CRITICAL();
   q->w_ptr = 0;
@@ -317,9 +332,13 @@ void process_can(uint8_t can_number) {
         CAN->sTxMailBox[0].TDHR = to_send.RDHR;
         CAN->sTxMailBox[0].TDTR = to_send.RDTR;
         CAN->sTxMailBox[0].TIR = to_send.RIR;
+
+        if (can_tx_check_min_slots_free(MAX_CAN_MSGS_PER_BULK_TRANSFER)) {
+          usb_outep3_resume_if_paused();
+        }
       }
     }
-
+    
     EXIT_CRITICAL();
   }
 }
@@ -405,6 +424,14 @@ void CAN3_TX_IRQ_Handler(void) { process_can(2); }
 void CAN3_RX0_IRQ_Handler(void) { can_rx(2); }
 void CAN3_SCE_IRQ_Handler(void) { can_sce(CAN3); }
 
+bool can_tx_check_min_slots_free(int min) {
+  return
+    can_slots_empty(&can_tx1_q) >= min &&
+    can_slots_empty(&can_tx2_q) >= min &&
+    can_slots_empty(&can_tx3_q) >= min &&
+    can_slots_empty(&can_txgmlan_q) >= min;
+}
+
 void can_send(CAN_FIFOMailBox_TypeDef *to_push, uint8_t bus_number, bool skip_tx_hook) {
   if (skip_tx_hook || safety_tx_hook(to_push) != 0) {
     if (bus_number < BUS_MAX) {

board/drivers/usb.h

@@ -23,12 +23,16 @@ typedef union _USB_Setup {
 }
 USB_Setup_TypeDef;
 
+#define MAX_CAN_MSGS_PER_BULK_TRANSFER 4
+
 void usb_init(void);
 int usb_cb_control_msg(USB_Setup_TypeDef *setup, uint8_t *resp, bool hardwired);
 int usb_cb_ep1_in(void *usbdata, int len, bool hardwired);
 void usb_cb_ep2_out(void *usbdata, int len, bool hardwired);
 void usb_cb_ep3_out(void *usbdata, int len, bool hardwired);
+void usb_cb_ep3_out_complete(void);
 void usb_cb_enumeration_complete(void);
+void usb_outep3_resume_if_paused(void);
 
 // **** supporting defines ****
 
@@ -380,6 +384,7 @@ USB_Setup_TypeDef setup;
 uint8_t usbdata[0x100];
 uint8_t* ep0_txdata = NULL;
 uint16_t ep0_txlen = 0;
+bool outep3_processing = false;
 
 // Store the current interface alt setting.
 int current_int0_alt_setting = 0;
@@ -744,6 +749,7 @@ void usb_irqhandler(void) {
       }
 
       if (endpoint == 3) {
+        outep3_processing = true;
         usb_cb_ep3_out(usbdata, len, 1);
       }
     } else if (status == STS_SETUP_UPDT) {
@@ -816,15 +822,17 @@ void usb_irqhandler(void) {
       #ifdef DEBUG_USB
         puts("  OUT3 PACKET XFRC\n");
       #endif
-      USBx_OUTEP(3)->DOEPTSIZ = (1U << 19) | 0x40U;
-      USBx_OUTEP(3)->DOEPCTL |= USB_OTG_DOEPCTL_EPENA | USB_OTG_DOEPCTL_CNAK;
+      // NAK cleared by process_can (if tx buffers have room)
+      outep3_processing = false;
+      usb_cb_ep3_out_complete();
     } else if ((USBx_OUTEP(3)->DOEPINT & 0x2000) != 0) {
       #ifdef DEBUG_USB
         puts("  OUT3 PACKET WTF\n");
       #endif
       // if NAK was set trigger this, unknown interrupt
-      USBx_OUTEP(3)->DOEPTSIZ = (1U << 19) | 0x40U;
-      USBx_OUTEP(3)->DOEPCTL |= USB_OTG_DOEPCTL_CNAK;
+      // TODO: why was this here? fires when TX buffers when we can't clear NAK
+      // USBx_OUTEP(3)->DOEPTSIZ = (1U << 19) | 0x40U;
+      // USBx_OUTEP(3)->DOEPCTL |= USB_OTG_DOEPCTL_CNAK;
     } else if ((USBx_OUTEP(3)->DOEPINT) != 0) {
       puts("OUTEP3 error ");
       puth(USBx_OUTEP(3)->DOEPINT);
@@ -932,6 +940,13 @@ void usb_irqhandler(void) {
   //USBx->GINTMSK = 0xFFFFFFFF & ~(USB_OTG_GINTMSK_NPTXFEM | USB_OTG_GINTMSK_PTXFEM | USB_OTG_GINTSTS_SOF | USB_OTG_GINTSTS_EOPF);
 }
 
+void usb_outep3_resume_if_paused() {
+  if (!outep3_processing && (USBx_OUTEP(3)->DOEPCTL & USB_OTG_DOEPCTL_NAKSTS) != 0) {
+    USBx_OUTEP(3)->DOEPTSIZ = (1U << 19) | 0x40U;
+    USBx_OUTEP(3)->DOEPCTL |= USB_OTG_DOEPCTL_EPENA | USB_OTG_DOEPCTL_CNAK;
+  }
+}
+
 void OTG_FS_IRQ_Handler(void) {
   NVIC_DisableIRQ(OTG_FS_IRQn);
   //__disable_irq();

board/main.c

@@ -235,6 +235,12 @@ void usb_cb_ep3_out(void *usbdata, int len, bool hardwired) {
   }
 }
 
+void usb_cb_ep3_out_complete() {
+  if (can_tx_check_min_slots_free(MAX_CAN_MSGS_PER_BULK_TRANSFER)) {
+    usb_outep3_resume_if_paused();
+  }
+}
+
 void usb_cb_enumeration_complete() {
   puts("USB enumeration complete\n");
   is_enumerated = 1;