f4 usb_hid: track whether we have buffers queued on endpoints

Make sure we don't clobber our endpoint configuration by
double configuring an Rx or Tx buffer against it.  Wait for
the completion of the previous operation before allowing
endpoint configuration again.

flight/PiOS/STM32F4xx/pios_usb_hid.c

@@ -40,6 +40,7 @@
 #include "pios_usbhook.h"	 /* PIOS_USBHOOK_* */
 
 #define MIN(x,y) (((x) < (y)) ? (x) : (y))
+#define MAX(x,y) (((x) > (y)) ? (x) : (y))
 
 static void PIOS_USB_HID_RegisterTxCallback(uint32_t usbhid_id, pios_com_callback tx_out_cb, uint32_t context);
 static void PIOS_USB_HID_RegisterRxCallback(uint32_t usbhid_id, pios_com_callback rx_in_cb, uint32_t context);
@@ -71,7 +72,10 @@ struct pios_usb_hid_dev {
 	bool usb_if_enabled;
 
 	uint8_t rx_packet_buffer[PIOS_USB_BOARD_HID_DATA_LENGTH];
+	bool rx_active;
+
 	uint8_t tx_packet_buffer[PIOS_USB_BOARD_HID_DATA_LENGTH];
+	bool tx_active;
 
 	uint32_t rx_dropped;
 	uint32_t rx_oversize;
@@ -140,6 +144,10 @@ int32_t PIOS_USB_HID_Init(uint32_t * usbhid_id, const struct pios_usb_hid_cfg *
 	usb_hid_dev->cfg = cfg;
 	usb_hid_dev->lower_id = lower_id;
 
+	/* Rx and Tx are not active yet */
+	usb_hid_dev->rx_active = false;
+	usb_hid_dev->tx_active = false;
+
 	/* Register class specific interface callbacks with the USBHOOK layer */
 	usb_hid_dev->usb_if_enabled = false;
 	PIOS_USBHOOK_RegisterIfOps(cfg->data_if, &usb_hid_ifops, (uint32_t) usb_hid_dev);
@@ -195,6 +203,12 @@ static bool PIOS_USB_HID_SendReport(struct pios_usb_hid_dev * usb_hid_dev)
 		return false;
 	}
 
+	/* 
+	 * Mark this endpoint as being tx active _before_ actually transmitting
+	 * to make sure we don't race with the Tx completion interrupt
+	 */
+	usb_hid_dev->tx_active = true;
+
 	/* Always set type as report ID */
 	usb_hid_dev->tx_packet_buffer[0] = 1;
 
@@ -240,16 +254,12 @@ static void PIOS_USB_HID_RxStart(uint32_t usbhid_id, uint16_t rx_bytes_avail) {
 	uint16_t max_payload_length = PIOS_USB_BOARD_HID_DATA_LENGTH - 2;
 #endif
 
-	PIOS_IRQ_Disable();
+	if (!usb_hid_dev->rx_active && (rx_bytes_avail >= max_payload_length)) {
-	if (rx_bytes_avail >= max_payload_length) {
-		/*
-		 * FIXME should make sure we do not already have a buffer queued
-		 */
 		PIOS_USBHOOK_EndpointRx(usb_hid_dev->cfg->data_rx_ep,
 					usb_hid_dev->rx_packet_buffer,
 					sizeof(usb_hid_dev->rx_packet_buffer));
+		usb_hid_dev->rx_active = true;
 	}
-	PIOS_IRQ_Enable();
 }
 
 static void PIOS_USB_HID_TxStart(uint32_t usbhid_id, uint16_t tx_bytes_avail)
@@ -268,7 +278,10 @@ static void PIOS_USB_HID_TxStart(uint32_t usbhid_id, uint16_t tx_bytes_avail)
 		return;
 	}
 
-	PIOS_USB_HID_SendReport(usb_hid_dev);
+	if (!usb_hid_dev->tx_active) {
+		/* Transmitter is not currently active, send a report */
+		PIOS_USB_HID_SendReport(usb_hid_dev);
+	}
 }
 
 static void PIOS_USB_HID_RegisterRxCallback(uint32_t usbhid_id, pios_com_callback rx_in_cb, uint32_t context)
@@ -434,11 +447,15 @@ static bool PIOS_USB_HID_EP_IN_Callback(uint32_t usb_hid_id, uint8_t epnum, uint
 		return false;
 	}
 
-	if (!PIOS_USB_CheckAvailable(usb_hid_dev->lower_id)) {
+	if (PIOS_USB_CheckAvailable(usb_hid_dev->lower_id) &&
+		PIOS_USB_HID_SendReport(usb_hid_dev)) {
+		/* More data has been queued, leave tx_active set to true */
+		return true;
+	} else {
+		/* Nothing new sent, transmitter is now inactive */
+		usb_hid_dev->tx_active = false;
 		return false;
 	}
-
-	return (PIOS_USB_HID_SendReport(usb_hid_dev));
 }
 
 /**
@@ -458,6 +475,7 @@ static bool PIOS_USB_HID_EP_OUT_Callback(uint32_t usb_hid_id, uint8_t epnum, uin
 
 	if (!usb_hid_dev->rx_in_cb) {
 		/* No Rx call back registered, disable the receiver */
+		usb_hid_dev->rx_active = false;
 		return false;
 	}
 
@@ -489,6 +507,7 @@ static bool PIOS_USB_HID_EP_OUT_Callback(uint32_t usb_hid_id, uint8_t epnum, uin
 		return true;
 	} else {
 		/* Not enough room left for a message, apply backpressure */
+		usb_hid_dev->rx_active = false;
 		return false;
 	}