I experienced major major data loss on a PL-2303 USB-serial converter
under 2.4.36, which I remedied by back-porting the pl2303.c from the
latest 2.6 kernel tree.

---

diff -u linux-2.4.36/drivers/usb/serial/pl2303.c.orig 
linux-2.4.36/drivers/usb/serial/pl2303.c
--- pl2303.c.orig       2008-01-01 22:36:40.000000000 +1030
+++ pl2303.c    2008-01-26 05:32:00.000000000 +1030
@@ -1,17 +1,20 @@
 /*
  * Prolific PL2303 USB to serial adaptor driver
  *
- * Copyright (C) 2001-2003 Greg Kroah-Hartman ([EMAIL PROTECTED])
+ * Copyright (C) 2001-2007 Greg Kroah-Hartman ([EMAIL PROTECTED])
  * Copyright (C) 2003 IBM Corp.
  *
  * Original driver for 2.2.x by anonymous
  *
- *     This program is free software; you can redistribute it and/or modify
- *     it under the terms of the GNU General Public License as published by
- *     the Free Software Foundation; either version 2 of the License, or
- *     (at your option) any later version.
+ *     This program is free software; you can redistribute it and/or
+ *     modify it under the terms of the GNU General Public License version
+ *     2 as published by the Free Software Foundation.
  *
  * See Documentation/usb/usb-serial.txt for more information on using this 
driver
+ * 2007_Jan_25 dn
+ *     Back-port pl2303.c from linux-2.6.23.14 - corrects major loss of
+ *     transmitted data, plus minor loss during close. [EMAIL PROTECTED]
+ *
  * 2003_Apr_24 gkh
  *     Added line error reporting support.  Hopefully it is correct...
  *
@@ -33,6 +36,9 @@
  * 
  */
 
+/* TODO first char sent is lost on second open of device.  anecdotal evidence
+ * TODO suggests this might be on all even opens of device. dn. */
+
 #include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -59,31 +65,60 @@
 /*
  * Version Information
  */
-#define DRIVER_VERSION "v0.10.1"       /* Takes from 2.6's */
 #define DRIVER_DESC "Prolific PL2303 USB to serial adaptor driver"
 
+#define PL2303_CLOSING_WAIT    (30*HZ)
 
+#define PL2303_BUF_SIZE                1024
+#define PL2303_TMP_BUF_SIZE    1024
+
+struct pl2303_buf {
+       unsigned int    buf_size;
+       char            *buf_buf;
+       char            *buf_get;
+       char            *buf_put;
+};
 
 static struct usb_device_id id_table [] = {
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ2) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_DCU11) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ3) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_PHAROS) },
        { USB_DEVICE(IODATA_VENDOR_ID, IODATA_PRODUCT_ID) },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_ID) },
        { USB_DEVICE(ATEN_VENDOR_ID2, ATEN_PRODUCT_ID) },
        { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID) },
+       { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID_UCSGT) },
        { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID) },
+       { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID_2080) },
        { USB_DEVICE(MA620_VENDOR_ID, MA620_PRODUCT_ID) },
        { USB_DEVICE(RATOC_VENDOR_ID, RATOC_PRODUCT_ID) },
        { USB_DEVICE(TRIPP_VENDOR_ID, TRIPP_PRODUCT_ID) },
        { USB_DEVICE(RADIOSHACK_VENDOR_ID, RADIOSHACK_PRODUCT_ID) },
        { USB_DEVICE(DCU10_VENDOR_ID, DCU10_PRODUCT_ID) },
        { USB_DEVICE(SITECOM_VENDOR_ID, SITECOM_PRODUCT_ID) },
+       { USB_DEVICE(ALCATEL_VENDOR_ID, ALCATEL_PRODUCT_ID) },
+       { USB_DEVICE(SAMSUNG_VENDOR_ID, SAMSUNG_PRODUCT_ID) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_SX1) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X65) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X75) },
+       { USB_DEVICE(SYNTECH_VENDOR_ID, SYNTECH_PRODUCT_ID) },
+       { USB_DEVICE(NOKIA_CA42_VENDOR_ID, NOKIA_CA42_PRODUCT_ID) },
+       { USB_DEVICE(CA_42_CA42_VENDOR_ID, CA_42_CA42_PRODUCT_ID) },
+       { USB_DEVICE(SAGEM_VENDOR_ID, SAGEM_PRODUCT_ID) },
+       { USB_DEVICE(LEADTEK_VENDOR_ID, LEADTEK_9531_PRODUCT_ID) },
+       { USB_DEVICE(SPEEDDRAGON_VENDOR_ID, SPEEDDRAGON_PRODUCT_ID) },
+       { USB_DEVICE(DATAPILOT_U2_VENDOR_ID, DATAPILOT_U2_PRODUCT_ID) },
+       { USB_DEVICE(BELKIN_VENDOR_ID, BELKIN_PRODUCT_ID) },
+       { USB_DEVICE(ALCOR_VENDOR_ID, ALCOR_PRODUCT_ID) },
+       { USB_DEVICE(HUAWEI_VENDOR_ID, HUAWEI_PRODUCT_ID) },
+       { USB_DEVICE(WS002IN_VENDOR_ID, WS002IN_PRODUCT_ID) },
        { }                                     /* Terminating entry */
 };
 
 MODULE_DEVICE_TABLE (usb, id_table);
 
-
 #define SET_LINE_REQUEST_TYPE          0x21
 #define SET_LINE_REQUEST               0x20
 
@@ -164,6 +199,8 @@
 
 struct pl2303_private {
        spinlock_t lock;
+       struct pl2303_buf *buf;
+       int write_urb_in_use;
        wait_queue_head_t delta_msr_wait;
        u8 line_control;
        u8 line_status;
@@ -171,6 +208,175 @@
        enum pl2303_type type;
 };
 
+/*
+ * pl2303_buf_alloc
+ *
+ * Allocate a circular buffer and all associated memory.
+ */
+static struct pl2303_buf *pl2303_buf_alloc(unsigned int size)
+{
+       struct pl2303_buf *pb;
+
+       if (size == 0)
+               return NULL;
+
+       pb = kmalloc(sizeof(struct pl2303_buf), GFP_KERNEL);
+       if (pb == NULL)
+               return NULL;
+
+       pb->buf_buf = kmalloc(size, GFP_KERNEL);
+       if (pb->buf_buf == NULL) {
+               kfree(pb);
+               return NULL;
+       }
+
+       pb->buf_size = size;
+       pb->buf_get = pb->buf_put = pb->buf_buf;
+
+       return pb;
+}
+
+/*
+ * pl2303_buf_free
+ *
+ * Free the buffer and all associated memory.
+ */
+static void pl2303_buf_free(struct pl2303_buf *pb)
+{
+       if (pb) {
+               kfree(pb->buf_buf);
+               kfree(pb);
+       }
+}
+
+/*
+ * pl2303_buf_clear
+ *
+ * Clear out all data in the circular buffer.
+ */
+static void pl2303_buf_clear(struct pl2303_buf *pb)
+{
+       if (pb != NULL)
+               pb->buf_get = pb->buf_put;
+               /* equivalent to a get of all data available */
+}
+
+/*
+ * pl2303_buf_data_avail
+ *
+ * Return the number of bytes of data available in the circular
+ * buffer.
+ */
+static unsigned int pl2303_buf_data_avail(struct pl2303_buf *pb)
+{
+       if (pb == NULL)
+               return 0;
+
+       return ((pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size);
+}
+
+/*
+ * pl2303_buf_space_avail
+ *
+ * Return the number of bytes of space available in the circular
+ * buffer.
+ */
+static unsigned int pl2303_buf_space_avail(struct pl2303_buf *pb)
+{
+       if (pb == NULL)
+               return 0;
+
+       return ((pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size);
+}
+
+static int copy_in(char *dest, int from_user, const char *source, unsigned 
count)
+{
+       if (!from_user)
+               memcpy (dest, source, count);
+       else if (copy_from_user (dest, source, count))
+               return -EFAULT;
+       return count;
+}
+
+/*
+ * pl2303_buf_put
+ *
+ * Copy data data from a user buffer and put it into the circular buffer.
+ * Restrict to the amount of space available.
+ *
+ * Return the number of bytes copied.
+ */
+static unsigned int pl2303_buf_put(struct pl2303_buf *pb, int from_user, const 
char *buf, unsigned int count)
+{
+       unsigned int len;
+
+       if (pb == NULL)
+               return 0;
+
+       len  = pl2303_buf_space_avail(pb);
+       if (count > len)
+               count = len;
+
+       if (count == 0)
+               return 0;
+
+       len = pb->buf_buf + pb->buf_size - pb->buf_put;
+       if (count > len) {
+               if (copy_in(pb->buf_put, from_user, buf, len) < 0)
+                       return -EFAULT;
+               if (copy_in(pb->buf_buf, from_user, buf+len, count - len) < 0)
+                       return -EFAULT;
+               pb->buf_put = pb->buf_buf + count - len;
+       } else {
+               if (copy_in(pb->buf_put, from_user, buf, count) < 0)
+                       return -EFAULT;
+               if (count < len)
+                       pb->buf_put += count;
+               else /* count == len */
+                       pb->buf_put = pb->buf_buf;
+       }
+
+       return count;
+}
+
+/*
+ * pl2303_buf_get
+ *
+ * Get data from the circular buffer and copy to the given buffer.
+ * Restrict to the amount of data available.
+ *
+ * Return the number of bytes copied.
+ */
+static unsigned int pl2303_buf_get(struct pl2303_buf *pb, char *buf,
+                                  unsigned int count)
+{
+       unsigned int len;
+
+       if (pb == NULL)
+               return 0;
+
+       len = pl2303_buf_data_avail(pb);
+       if (count > len)
+               count = len;
+
+       if (count == 0)
+               return 0;
+
+       len = pb->buf_buf + pb->buf_size - pb->buf_get;
+       if (count > len) {
+               memcpy(buf, pb->buf_get, len);
+               memcpy(buf+len, pb->buf_buf, count - len);
+               pb->buf_get = pb->buf_buf + count - len;
+       } else {
+               memcpy(buf, pb->buf_get, count);
+               if (count < len)
+                       pb->buf_get += count;
+               else /* count == len */
+                       pb->buf_get = pb->buf_buf;
+       }
+
+       return count;
+}
 
 static int pl2303_startup (struct usb_serial *serial)
 {
@@ -191,14 +397,28 @@
        for (i = 0; i < serial->num_ports; ++i) {
                priv = kmalloc (sizeof (struct pl2303_private), GFP_KERNEL);
                if (!priv)
-                       return -ENOMEM;
+                       goto cleanup;
                memset (priv, 0x00, sizeof (struct pl2303_private));
                spin_lock_init(&priv->lock);
+               priv->buf = pl2303_buf_alloc(PL2303_BUF_SIZE);
+               if (priv->buf == NULL) {
+                       kfree(priv);
+                       goto cleanup;
+               }
                init_waitqueue_head(&priv->delta_msr_wait);
                usb_set_serial_port_data(&serial->port[i], priv);
                priv->type = type;
        }
        return 0;
+
+cleanup:
+       for (--i; i>=0; --i) {
+               priv = usb_get_serial_port_data(&serial->port[i]);
+               pl2303_buf_free(priv->buf);
+               kfree(priv);
+               usb_set_serial_port_data(&serial->port[i], NULL);
+       }
+       return -ENOMEM;
 }
 
 static int set_control_lines (struct usb_device *dev, u8 value)
@@ -212,42 +432,65 @@
        return retval;
 }
 
-static int pl2303_write (struct usb_serial_port *port, int from_user,  const 
unsigned char *buf, int count)
+static void pl2303_send(struct usb_serial_port *port)
 {
-       int result;
+       int count, result;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
 
-       dbg("%s - port %d, %d bytes", __FUNCTION__, port->number, count);
+       dbg("%s - port %d", __FUNCTION__, port->number);
 
-       if (!count)
-               return count;
+       spin_lock_irqsave(&priv->lock, flags);
 
-       if (port->write_urb->status == -EINPROGRESS) {
-               dbg("%s - already writing", __FUNCTION__);
-               return 0;
+       if (priv->write_urb_in_use) {
+               spin_unlock_irqrestore(&priv->lock, flags);
+               return;
        }
 
-       count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
-       if (from_user) {
-               if (copy_from_user (port->write_urb->transfer_buffer, buf, 
count))
-                       return -EFAULT;
-       } else {
-               memcpy (port->write_urb->transfer_buffer, buf, count);
+       count = pl2303_buf_get(priv->buf, port->write_urb->transfer_buffer,
+                              port->bulk_out_size);
+
+       if (count == 0) {
+               spin_unlock_irqrestore(&priv->lock, flags);
+               return;
        }
        
+       priv->write_urb_in_use = 1;
+
+       spin_unlock_irqrestore(&priv->lock, flags);
+
        usb_serial_debug_data (__FILE__, __FUNCTION__, count, 
port->write_urb->transfer_buffer);
 
        port->write_urb->transfer_buffer_length = count;
        port->write_urb->dev = port->serial->dev;
        result = usb_submit_urb (port->write_urb);
-       if (result)
+       if (result) {
                err("%s - failed submitting write urb, error %d", __FUNCTION__, 
result);
-       else
-               result = count;
+               priv->write_urb_in_use = 0;
+               // TODO: reschedule pl2303_send
+       }
 
-       return result;
+       wake_up_interruptible(&port->tty->write_wait);  /* this, at very least, 
wakes up pl2303_close */
 }
+ 
+static int pl2303_write (struct usb_serial_port *port, int from_user, const 
unsigned char *buf, int count)
+{
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
 
+       dbg("%s - port %d, %d bytes", __FUNCTION__, port->number, count);
+
+       if (!count)
+               return count;
+
+       spin_lock_irqsave(&priv->lock, flags);
+       count = pl2303_buf_put(priv->buf, from_user, buf, count);
+       spin_unlock_irqrestore(&priv->lock, flags);
 
+       pl2303_send(port);
+
+       return count;
+}
 
 static void pl2303_set_termios (struct usb_serial_port *port, struct termios 
*old_termios)
 {
@@ -278,6 +521,7 @@
 
        cflag = port->tty->termios->c_cflag;
        /* check that they really want us to change something */
+       /* important to do this as even a null change can corrupt data in 
transit */
        if (old_termios) {
                if ((cflag == old_termios->c_cflag) &&
                    (RELEVANT_IFLAG(port->tty->termios->c_iflag) == 
RELEVANT_IFLAG(old_termios->c_iflag))) {
@@ -299,7 +543,6 @@
        dbg ("0xa1:0x21:0:0  %d - %x %x %x %x %x %x %x", i,
             buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6]);
 
-
        if (cflag & CSIZE) {
                switch (cflag & CSIZE) {
                        case CS5:       buf[6] = 5;     break;
@@ -311,28 +554,7 @@
                dbg("%s - data bits = %d", __FUNCTION__, buf[6]);
        }
 
-       baud = 0;
-       switch (cflag & CBAUD) {
-               case B0:        baud = 0;       break;
-               case B75:       baud = 75;      break;
-               case B150:      baud = 150;     break;
-               case B300:      baud = 300;     break;
-               case B600:      baud = 600;     break;
-               case B1200:     baud = 1200;    break;
-               case B1800:     baud = 1800;    break;
-               case B2400:     baud = 2400;    break;
-               case B4800:     baud = 4800;    break;
-               case B9600:     baud = 9600;    break;
-               case B19200:    baud = 19200;   break;
-               case B38400:    baud = 38400;   break;
-               case B57600:    baud = 57600;   break;
-               case B115200:   baud = 115200;  break;
-               case B230400:   baud = 230400;  break;
-               case B460800:   baud = 460800;  break;
-               default:
-                       err ("pl2303 driver does not support the baudrate 
requested (fix it)");
-                       break;
-       }
+       baud = tty_get_baud_rate(port->tty);
        dbg("%s - baud = %d", __FUNCTION__, baud);
        if (baud) {
                buf[0] = baud & 0xff;
@@ -410,6 +632,13 @@
                                    VENDOR_WRITE_REQUEST_TYPE,
                                    0x0, index, NULL, 0, 100);
                dbg ("0x40:0x1:0x0:0x%x  %d", index, i);
+       } else {
+               i = usb_control_msg(serial->dev,
+                                   usb_sndctrlpipe(serial->dev, 0),
+                                   VENDOR_WRITE_REQUEST,
+                                   VENDOR_WRITE_REQUEST_TYPE,
+                                   0x0, 0x0, NULL, 0, 100);
+               dbg ("0x40:0x1:0x0:0x0  %d", i);
        }
 
        kfree (buf);
@@ -420,8 +649,8 @@
 {
        struct termios tmp_termios;
        struct usb_serial *serial = port->serial;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned char *buf;
-       struct pl2303_private *priv = port->private;
        int result;
 
        if (port_paranoia_check (port, __FUNCTION__))
@@ -429,8 +658,10 @@
                
        dbg("%s -  port %d", __FUNCTION__, port->number);
 
-       usb_clear_halt(serial->dev, port->write_urb->pipe);
-       usb_clear_halt(serial->dev, port->read_urb->pipe);
+       if (priv->type != HX) {
+               usb_clear_halt(serial->dev, port->write_urb->pipe);
+               usb_clear_halt(serial->dev, port->read_urb->pipe);
+       }
 
        buf = kmalloc(10, GFP_KERNEL);
        if (buf==NULL)
@@ -500,10 +731,12 @@
 static void pl2303_close (struct usb_serial_port *port, struct file *filp)
 {
        struct usb_serial *serial;
-       struct pl2303_private *priv;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int c_cflag;
        int result;
+       long timeout;
+       wait_queue_t wait;
 
        if (port_paranoia_check (port, __FUNCTION__))
                return;
@@ -513,6 +746,43 @@
        
        dbg("%s - port %d", __FUNCTION__, port->number);
 
+       /* wait for data to drain from the buffer */
+       spin_lock_irqsave(&priv->lock, flags);
+       timeout = PL2303_CLOSING_WAIT;
+       init_waitqueue_entry(&wait, current);
+       add_wait_queue(&port->tty->write_wait, &wait);
+       for (;;) {
+               dbg("%s - buf_data_avail %d",
+                   __FUNCTION__, pl2303_buf_data_avail(priv->buf));
+               set_current_state(TASK_INTERRUPTIBLE);
+               if (pl2303_buf_data_avail(priv->buf) == 0 ||
+                   timeout == 0 || signal_pending(current))
+                       break;
+               spin_unlock_irqrestore(&priv->lock, flags);
+               timeout = schedule_timeout(timeout);
+               spin_lock_irqsave(&priv->lock, flags);
+       }
+       set_current_state(TASK_RUNNING);
+       remove_wait_queue(&port->tty->write_wait, &wait);
+       /* clear out any remaining data in the buffer */
+       pl2303_buf_clear(priv->buf);
+       spin_unlock_irqrestore(&priv->lock, flags);
+
+       /* wait for characters to drain from the device */
+       /* (this is long enough for the entire 256 byte */
+       /* pl2303 hardware buffer to drain with no flow */
+       /* control for data rates of 1200 bps or more, */
+       /* for lower rates we should really know how much */
+       /* data is in the buffer to compute a delay */
+       /* that is not unnecessarily long) */
+       int bps = tty_get_baud_rate(port->tty);
+       if (bps > 1200)
+               timeout = max((HZ*2560)/bps,HZ/10);
+       else
+               timeout = 2*HZ;
+       set_current_state(TASK_INTERRUPTIBLE);
+       schedule_timeout(timeout);
+
        if (serial->dev) {
                if (port->tty) {
                        c_cflag = port->tty->termios->c_cflag;
@@ -700,34 +970,68 @@
                dbg("%s - error sending break = %d", __FUNCTION__, result);
 }
 
-
 static void pl2303_shutdown (struct usb_serial *serial)
 {
        int i;
+       struct pl2303_private *priv;
 
        dbg("%s", __FUNCTION__);
 
        for (i = 0; i < serial->num_ports; ++i) {
-               kfree (usb_get_serial_port_data(&serial->port[i]));
-               usb_set_serial_port_data(&serial->port[i], NULL);
-       }               
+               priv = usb_get_serial_port_data(&serial->port[i]);
+               if (priv) {
+                       pl2303_buf_free(priv->buf);
+                       kfree(priv);
+                       usb_set_serial_port_data(&serial->port[i], NULL);
+               }
+       }
 }
 
+static void pl2303_update_line_status(struct usb_serial_port *port,
+                                     unsigned char *data,
+                                     unsigned int actual_length)
+{
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
+       u8 status_idx = UART_STATE;
+       u8 length = UART_STATE + 1;
+       u16 idv, idp;
+
+       idv = le16_to_cpu(port->serial->dev->descriptor.idVendor);
+       idp = le16_to_cpu(port->serial->dev->descriptor.idProduct);
+
+
+       if (idv == SIEMENS_VENDOR_ID) {
+               if (idp == SIEMENS_PRODUCT_ID_X65 ||
+                   idp == SIEMENS_PRODUCT_ID_SX1 ||
+                   idp == SIEMENS_PRODUCT_ID_X75) {
+
+                       length = 1;
+                       status_idx = 0;
+               }
+       }
+
+       if (actual_length < length)
+               return;
+
+        /* Save off the uart status for others to look at */
+       spin_lock_irqsave(&priv->lock, flags);
+       priv->line_status = data[status_idx];
+       spin_unlock_irqrestore(&priv->lock, flags);
+       wake_up_interruptible(&priv->delta_msr_wait);
+}
 
 static void pl2303_read_int_callback (struct urb *urb)
 {
        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
-       struct usb_serial *serial = get_usb_serial (port, __FUNCTION__);
-       struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned char *data = urb->transfer_buffer;
-       unsigned long flags;
-       u8 uart_state;
+       int status = urb->status;
 
        dbg("%s (%d)", __FUNCTION__, port->number);
 
        /* ints auto restart... */
 
-       switch (urb->status) {
+       switch (status) {
        case 0:
                /* success */
                break;
@@ -735,34 +1039,26 @@
        case -ENOENT:
        case -ESHUTDOWN:
                /* this urb is terminated, clean up */
-               dbg("%s - urb shutting down with status: %d", __FUNCTION__, 
urb->status);
+               dbg("%s - urb shutting down with status: %d", __FUNCTION__, 
status);
                return;
        default:
-               dbg("%s - nonzero urb status received: %d", __FUNCTION__, 
urb->status);
-               return;
-       }
-
-       if (!serial) {
-               return;
+               dbg("%s - nonzero urb status received: %d", __FUNCTION__, 
status);
+               goto exit;
        }
 
        usb_serial_debug_data (__FILE__, __FUNCTION__, urb->actual_length, 
urb->transfer_buffer);
 
-       if (urb->actual_length < UART_STATE)
-               return;
-
-       /* Save off the uart status for others to look at */
-       uart_state = data[UART_STATE];
-       spin_lock_irqsave(&priv->lock, flags);
-       uart_state |= (priv->line_status & UART_STATE_TRANSIENT_MASK);
-       priv->line_status = uart_state;
-       spin_unlock_irqrestore(&priv->lock, flags);
-       wake_up_interruptible (&priv->delta_msr_wait);
+       pl2303_update_line_status(port, data, urb->actual_length);
 
+exit:
+       status = usb_submit_urb(urb);
+       if (status)
+               err("%s - usb_submit_urb failed with result %d\n", 
__FUNCTION__, status);
+       else
+               dbg("%s - usb_submit_urb succeeded.  peaches.", __FUNCTION__);
        return;
 }
 
-
 static void pl2303_read_bulk_callback (struct urb *urb)
 {
        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
@@ -773,12 +1069,10 @@
        unsigned long flags;
        int i;
        int result;
-       u8 status;
+       int status = urb->status;
+       u8 line_status;
        char tty_flag;
 
-       if (port_paranoia_check (port, __FUNCTION__))
-               return;
-
        dbg("%s - port %d", __FUNCTION__, port->number);
 
        if (!serial) {
@@ -786,17 +1080,16 @@
                return;
        }
 
-       if (urb->status) {
-               dbg("%s - urb->status = %d", __FUNCTION__, urb->status);
+       if (status) {
+               dbg("%s - status = %d", __FUNCTION__, status);
                if (!port->open_count) {
                        dbg("%s - port is closed, exiting.", __FUNCTION__);
                        return;
                }
-               if (urb->status == -EPROTO) {
+               if (status == -EPROTO) {
                        /* PL2303 mysteriously fails with -EPROTO reschedule 
the read */
                        dbg("%s - caught -EPROTO, resubmitting the urb", 
__FUNCTION__);
-                       urb->status = 0;
-                       urb->dev = serial->dev;
+                       urb->dev = port->serial->dev;
                        result = usb_submit_urb(urb);
                        if (result)
                                err("%s - failed resubmitting read urb, error 
%d", __FUNCTION__, result);
@@ -812,25 +1105,25 @@
        tty_flag = TTY_NORMAL;
 
        spin_lock_irqsave(&priv->lock, flags);
-       status = priv->line_status;
+       line_status = priv->line_status;
        priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
        spin_unlock_irqrestore(&priv->lock, flags);
-       wake_up_interruptible (&priv->delta_msr_wait); //AF from 2.6
+       wake_up_interruptible (&priv->delta_msr_wait);
 
        /* break takes precedence over parity, */
        /* which takes precedence over framing errors */
-       if (status & UART_BREAK_ERROR )
+       if (line_status & UART_BREAK_ERROR )
                tty_flag = TTY_BREAK;
-       else if (status & UART_PARITY_ERROR)
+       else if (line_status & UART_PARITY_ERROR)
                tty_flag = TTY_PARITY;
-       else if (status & UART_FRAME_ERROR)
+       else if (line_status & UART_FRAME_ERROR)
                tty_flag = TTY_FRAME;
        dbg("%s - tty_flag = %d", __FUNCTION__, tty_flag);
 
        tty = port->tty;
        if (tty && urb->actual_length) {
                /* overrun is special, not associated with a char */
-               if (status & UART_OVERRUN_ERROR)
+               if (line_status & UART_OVERRUN_ERROR)
                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 
                for (i = 0; i < urb->actual_length; ++i) {
@@ -844,7 +1137,7 @@
 
        /* Schedule the next read _if_ we are still open */
        if (port->open_count) {
-               urb->dev = serial->dev;
+               urb->dev = port->serial->dev;
                result = usb_submit_urb(urb);
                if (result)
                        err("%s - failed resubmitting read urb, error %d", 
__FUNCTION__, result);
@@ -853,38 +1146,50 @@
        return;
 }
 
-
-
 static void pl2303_write_bulk_callback (struct urb *urb)
 {
        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
        int result;
+       int status = urb->status;
 
        if (port_paranoia_check (port, __FUNCTION__))
                return;
        
        dbg("%s - port %d", __FUNCTION__, port->number);
        
-       if (urb->status) {
+       switch (status) {
+       case 0:
+               /* success */
+               break;
+       case -ECONNRESET:
+       case -ENOENT:
+       case -ESHUTDOWN:
+               /* this urb is terminated, clean up */
+               dbg("%s - urb shutting down with status: %d", __FUNCTION__,
+                   status);
+               priv->write_urb_in_use = 0;
+               return;
+       default:
                /* error in the urb, so we have to resubmit it */
                if (serial_paranoia_check (port->serial, __FUNCTION__)) {
                        return;
                }
                dbg("%s - Overflow in write", __FUNCTION__);
-               dbg("%s - nonzero write bulk status received: %d", 
__FUNCTION__, urb->status);
+               dbg("%s - nonzero write bulk status received: %d", 
__FUNCTION__, status);
                port->write_urb->transfer_buffer_length = 1;
                port->write_urb->dev = port->serial->dev;
                result = usb_submit_urb (port->write_urb);
                if (result)
                        err("%s - failed resubmitting write urb, error %d", 
__FUNCTION__, result);
-
-               return;
+               else
+                       return;
        }
 
-       queue_task(&port->tqueue, &tq_immediate);
-       mark_bh(IMMEDIATE_BH);
+       priv->write_urb_in_use = 0;
 
-       return;
+       /* send any buffered data */
+       pl2303_send(port);
 }
 
 
@@ -894,19 +1199,17 @@
        retval = usb_serial_register(&pl2303_device);
        if (retval)
                goto failed_usb_serial_register;
-       info(DRIVER_DESC " " DRIVER_VERSION);
+       info(DRIVER_DESC);
        return 0;
 failed_usb_serial_register:
        return retval;
 }
 
-
 static void __exit pl2303_exit (void)
 {
        usb_serial_deregister (&pl2303_device);
 }
 
-
 module_init(pl2303_init);
 module_exit(pl2303_exit);
 


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