---

yaml
---
r: 354275
b: refs/heads/master
c: 06b8f14
h: refs/heads/master
i:
  354273: 4d35dca
  354271: e52b6ec
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b360cb9726ce04480840e279150a907c21837334
+refs/heads/master: 06b8f14dc2649ee12ff5194fc562d74353c8b4ba

trunk/drivers/staging/fwserial/fwserial.c

@@ -40,12 +40,10 @@ static int num_ttys = 4;	    /* # of std ttys to create per fw_card    */
 				    /* - doubles as loopback port index       */
 static bool auto_connect = true;    /* try to VIRT_CABLE to every peer        */
 static bool create_loop_dev = true; /* create a loopback device for each card */
-bool limit_bw;			    /* limit async bandwidth to 20% of max    */
 
 module_param_named(ttys, num_ttys, int, S_IRUGO | S_IWUSR);
 module_param_named(auto, auto_connect, bool, S_IRUGO | S_IWUSR);
 module_param_named(loop, create_loop_dev, bool, S_IRUGO | S_IWUSR);
-module_param(limit_bw, bool, S_IRUGO | S_IWUSR);
 
 /*
  * Threshold below which the tty is woken for writing
@@ -2940,4 +2938,3 @@ MODULE_DEVICE_TABLE(ieee1394, fwserial_id_table);
 MODULE_PARM_DESC(ttys, "Number of ttys to create for each local firewire node");
 MODULE_PARM_DESC(auto, "Auto-connect a tty to each firewire node discovered");
 MODULE_PARM_DESC(loop, "Create a loopback device, fwloop<n>, with ttys");
-MODULE_PARM_DESC(limit_bw, "Limit bandwidth utilization to 20%.");

trunk/drivers/staging/fwserial/fwserial.h

@@ -351,7 +351,6 @@ struct fw_serial {
 #define TTY_DEV_NAME		    "fwtty"	/* ttyFW was taken           */
 static const char tty_dev_name[] =  TTY_DEV_NAME;
 static const char loop_dev_name[] = "fwloop";
-extern bool limit_bw;
 
 struct tty_driver *fwtty_driver;
 
@@ -370,18 +369,16 @@ static inline void fwtty_bind_console(struct fwtty_port *port,
 
 /*
  * Returns the max send async payload size in bytes based on the unit device
- * link speed - if set to limit bandwidth to max 20%, use lookup table
+ * link speed. Self-limiting asynchronous bandwidth (via reducing the payload)
+ * is not necessary and does not work, because
+ *   1) asynchronous traffic will absorb all available bandwidth (less that
+ *	being used for isochronous traffic)
+ *   2) isochronous arbitration always wins.
  */
 static inline int link_speed_to_max_payload(unsigned speed)
 {
-	static const int max_async[] = { 307, 614, 1229, 2458, };
-	BUILD_BUG_ON(ARRAY_SIZE(max_async) - 1 != SCODE_800);
-
 	speed = clamp(speed, (unsigned) SCODE_100, (unsigned) SCODE_800);
-	if (limit_bw)
-		return max_async[speed];
-	else
-		return 1 << (speed + 9);
+	return 1 << (speed + 9);
 }
 
 #endif /* _FIREWIRE_FWSERIAL_H */