USB: serial: garmin_gps: fixes package loss if used from gpsbabel

This patch contains two fixes submitted by Ondrej Palkovsky:
- the 'ACK' packet is sent after the transfer of the USB packet is
completed, i.e. in the write_callback function. Because the close
function sends the 'abort' command, a parameter is added that allows
the caller of garmin_write_bulk to specify, if the 'ack' should be
propagated to the serial link or dimissed.
This fixes the problem with gpsbabel, it has sent several packets that
were acknowledged before they were sent to the GPS and GpsBabel closed
the device - thus effectively cancelled all outstanding requests in the
queue.
- removed the APP_RESP_SEEN and APP_REQ_SEEN flags and changed
them into counters. It evades USB reset of the gps on every device close.
Signed-off-by: Hermann Kneissel <hermann.kneissel@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/garmin_gps.c

 /*
  * Garmin GPS driver
  *
- * Copyright (C) 2006 Hermann Kneissel herkne@users.sourceforge.net
+ * Copyright (C) 2006,2007 Hermann Kneissel herkne@users.sourceforge.net
  *
  * The latest version of the driver can be found at
  * http://sourceforge.net/projects/garmin-gps/
@@ -34,6 +34,7 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <asm/uaccess.h>
+#include <asm/atomic.h>
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 
@@ -52,7 +53,7 @@ static int debug = 0;
  */
 
 #define VERSION_MAJOR	0
-#define VERSION_MINOR	28
+#define VERSION_MINOR	31
 
 #define _STR(s) #s
 #define _DRIVER_VERSION(a,b) "v" _STR(a) "." _STR(b)
@@ -141,6 +142,8 @@ struct garmin_data {
 	__u8   inbuffer [GPS_IN_BUFSIZ];  /* tty -> usb */
 	__u8   outbuffer[GPS_OUT_BUFSIZ]; /* usb -> tty */
 	__u8   privpkt[4*6];
+	atomic_t req_count;
+	atomic_t resp_count;
 	spinlock_t lock;
 	struct list_head pktlist;
 };
@@ -171,8 +174,6 @@ struct garmin_data {
 #define CLEAR_HALT_REQUIRED       0x0001
 
 #define FLAGS_QUEUING             0x0100
-#define FLAGS_APP_RESP_SEEN       0x0200
-#define FLAGS_APP_REQ_SEEN        0x0400
 #define FLAGS_DROP_DATA           0x0800
 
 #define FLAGS_GSP_SKIP            0x1000
@@ -186,7 +187,8 @@ struct garmin_data {
 /* function prototypes */
 static void gsp_next_packet(struct garmin_data * garmin_data_p);
 static int  garmin_write_bulk(struct usb_serial_port *port,
-			     const unsigned char *buf, int count);
+			     const unsigned char *buf, int count,
+			     int dismiss_ack);
 
 /* some special packets to be send or received */
 static unsigned char const GARMIN_START_SESSION_REQ[]
@@ -233,9 +235,7 @@ static struct usb_driver garmin_driver = {
 
 static inline int noResponseFromAppLayer(struct garmin_data * garmin_data_p)
 {
-	return ((garmin_data_p->flags
-				& (FLAGS_APP_REQ_SEEN|FLAGS_APP_RESP_SEEN))
-	        == FLAGS_APP_REQ_SEEN);
+	return atomic_read(&garmin_data_p->req_count) == atomic_read(&garmin_data_p->resp_count);
 }
 
 
@@ -463,7 +463,7 @@ static int gsp_rec_packet(struct garmin_data * garmin_data_p, int count)
 	usbdata[2] = __cpu_to_le32(size);
 
 	garmin_write_bulk (garmin_data_p->port, garmin_data_p->inbuffer,
-			   GARMIN_PKTHDR_LENGTH+size);
+			   GARMIN_PKTHDR_LENGTH+size, 0);
 
 	/* if this was an abort-transfer command, flush all
 	   queued data. */
@@ -818,7 +818,7 @@ static int nat_receive(struct garmin_data * garmin_data_p,
 			if (garmin_data_p->insize >= len) {
 				garmin_write_bulk (garmin_data_p->port,
 				                   garmin_data_p->inbuffer,
-				                   len);
+				                   len, 0);
 				garmin_data_p->insize = 0;
 
 				/* if this was an abort-transfer command,
@@ -893,10 +893,11 @@ static int garmin_clear(struct garmin_data * garmin_data_p)
 
 	struct usb_serial_port *port = garmin_data_p->port;
 
-	if (port != NULL && garmin_data_p->flags & FLAGS_APP_RESP_SEEN) {
+	if (port != NULL && atomic_read(&garmin_data_p->resp_count)) {
 		/* send a terminate command */
 		status = garmin_write_bulk(port, GARMIN_STOP_TRANSFER_REQ,
-		                           sizeof(GARMIN_STOP_TRANSFER_REQ));
+		                           sizeof(GARMIN_STOP_TRANSFER_REQ),
+					   1);
 	}
 
 	/* flush all queued data */
@@ -939,7 +940,8 @@ static int garmin_init_session(struct usb_serial_port *port)
 		dbg("%s - starting session ...", __FUNCTION__);
 		garmin_data_p->state = STATE_ACTIVE;
 		status = garmin_write_bulk(port, GARMIN_START_SESSION_REQ,
-		                           sizeof(GARMIN_START_SESSION_REQ));
+		                           sizeof(GARMIN_START_SESSION_REQ),
+					   0);
 
 		if (status >= 0) {
 
@@ -950,7 +952,8 @@ static int garmin_init_session(struct usb_serial_port *port)
 			/* not needed, but the win32 driver does it too ... */
 			status = garmin_write_bulk(port,
 						   GARMIN_START_SESSION_REQ2,
-			                           sizeof(GARMIN_START_SESSION_REQ2));
+			                           sizeof(GARMIN_START_SESSION_REQ2),
+						   0);
 			if (status >= 0) {
 				status = 0;
 				spin_lock_irqsave(&garmin_data_p->lock, flags);
@@ -987,6 +990,8 @@ static int garmin_open (struct usb_serial_port *port, struct file *filp)
 	garmin_data_p->mode  = initial_mode;
 	garmin_data_p->count = 0;
 	garmin_data_p->flags = 0;
+	atomic_set(&garmin_data_p->req_count, 0);
+	atomic_set(&garmin_data_p->resp_count, 0);
 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
 
 	/* shutdown any bulk reads that might be going on */
@@ -1035,28 +1040,39 @@ static void garmin_write_bulk_callback (struct urb *urb)
 {
 	unsigned long flags;
 	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
-	struct garmin_data * garmin_data_p = usb_get_serial_port_data(port);
 	int status = urb->status;
 
-	/* free up the transfer buffer, as usb_free_urb() does not do this */
-	kfree (urb->transfer_buffer);
+	if (port) {
+		struct garmin_data * garmin_data_p = usb_get_serial_port_data(port);
 
 		dbg("%s - port %d", __FUNCTION__, port->number);
 
+		if (GARMIN_LAYERID_APPL == getLayerId(urb->transfer_buffer)
+		    && (garmin_data_p->mode == MODE_GARMIN_SERIAL))  {
+			gsp_send_ack(garmin_data_p, ((__u8 *)urb->transfer_buffer)[4]);
+		}
+
 		if (status) {
 			dbg("%s - nonzero write bulk status received: %d",
-			__FUNCTION__, status);
+			    __FUNCTION__, urb->status);
 			spin_lock_irqsave(&garmin_data_p->lock, flags);
 			garmin_data_p->flags |= CLEAR_HALT_REQUIRED;
 			spin_unlock_irqrestore(&garmin_data_p->lock, flags);
 		}
 
 		usb_serial_port_softint(port);
+	}
+
+	/* Ignore errors that resulted from garmin_write_bulk with dismiss_ack=1 */
+
+	/* free up the transfer buffer, as usb_free_urb() does not do this */
+	kfree (urb->transfer_buffer);
 }
 
 
 static int garmin_write_bulk (struct usb_serial_port *port,
-			      const unsigned char *buf, int count)
+			      const unsigned char *buf, int count,
+			      int dismiss_ack)
 {
 	unsigned long flags;
 	struct usb_serial *serial = port->serial;
@@ -1093,13 +1109,12 @@ static int garmin_write_bulk (struct usb_serial_port *port,
 			 	usb_sndbulkpipe (serial->dev,
 				port->bulk_out_endpointAddress),
 				buffer, count,
-				garmin_write_bulk_callback, port);
+				garmin_write_bulk_callback,
+				dismiss_ack ? NULL : port);
 	urb->transfer_flags |= URB_ZERO_PACKET;
 
 	if (GARMIN_LAYERID_APPL == getLayerId(buffer)) {
-		spin_lock_irqsave(&garmin_data_p->lock, flags);
-		garmin_data_p->flags |= FLAGS_APP_REQ_SEEN;
-		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+		atomic_inc(&garmin_data_p->req_count);
 		if (garmin_data_p->mode == MODE_GARMIN_SERIAL)  {
 			pkt_clear(garmin_data_p);
 			garmin_data_p->state = STATE_GSP_WAIT_DATA;
@@ -1114,13 +1129,6 @@ static int garmin_write_bulk (struct usb_serial_port *port,
 		        "failed with status = %d\n",
 				__FUNCTION__, status);
 		count = status;
-	} else {
-
-		if (GARMIN_LAYERID_APPL == getLayerId(buffer)
-		    && (garmin_data_p->mode == MODE_GARMIN_SERIAL))  {
-
-			gsp_send_ack(garmin_data_p, buffer[4]);
-		}
 	}
 
 	/* we are done with this urb, so let the host driver
@@ -1135,7 +1143,6 @@ static int garmin_write_bulk (struct usb_serial_port *port,
 static int garmin_write (struct usb_serial_port *port,
 			 const unsigned char *buf, int count)
 {
-	unsigned long flags;
 	int pktid, pktsiz, len;
 	struct garmin_data * garmin_data_p = usb_get_serial_port_data(port);
 	__le32 *privpkt = (__le32 *)garmin_data_p->privpkt;
@@ -1186,9 +1193,7 @@ static int garmin_write (struct usb_serial_port *port,
 				break;
 
 			case PRIV_PKTID_RESET_REQ:
-				spin_lock_irqsave(&garmin_data_p->lock, flags);
-				garmin_data_p->flags |= FLAGS_APP_REQ_SEEN;
-				spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+				atomic_inc(&garmin_data_p->req_count);
 				break;
 
 			case PRIV_PKTID_SET_DEF_MODE:
@@ -1241,8 +1246,6 @@ static int garmin_chars_in_buffer (struct usb_serial_port *port)
 static void garmin_read_process(struct garmin_data * garmin_data_p,
 				 unsigned char *data, unsigned data_length)
 {
-	unsigned long flags;
-
 	if (garmin_data_p->flags & FLAGS_DROP_DATA) {
 		/* abort-transfer cmd is actice */
 		dbg("%s - pkt dropped", __FUNCTION__);
@@ -1254,9 +1257,7 @@ static void garmin_read_process(struct garmin_data * garmin_data_p,
 		   the device */
 		if (0 == memcmp(data, GARMIN_APP_LAYER_REPLY,
 		                sizeof(GARMIN_APP_LAYER_REPLY))) {
-			spin_lock_irqsave(&garmin_data_p->lock, flags);
-			garmin_data_p->flags |= FLAGS_APP_RESP_SEEN;
-			spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+			atomic_inc(&garmin_data_p->resp_count);
 		}
 
 		/* if throttling is active or postprecessing is required