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Staging: quatech_usb2: chars_in_buffer() fix 

It seems I can't count.

Patch to fix chars_in_buffer() method (broken in vendor driver), and
subsequently simplify the close() method, making it somewhat less
broken. There is quite a bit more improvement to do on this method
though.

Signed-off-by: Richard Ash <richard@audacityteam.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Richard Ash 2009-08-17 10:43:49 +01:00 committed by Greg Kroah-Hartman
parent dbe2481580
commit 2feb633d65
1 changed files with 12 additions and 29 deletions
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41
drivers/staging/quatech_usb2/quatech_usb2.c
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@ -619,7 +619,10 @@ int qt2_open(struct tty_struct *tty, struct usb_serial_port *port)
return 0;
}
/* called when a port is closed by userspace */
/* called when a port is closed by userspace. It won't be called, however,
* until calls to chars_in_buffer() reveal that the port has completed
* sending buffered data, and there is nothing else to do. Thus we don't have
* to rely on forcing data through in this function. */
/* Setting close_pending should keep new data from being written out,
* once all the data in the enpoint buffers is moved out we won't get
* any more. */
@ -644,26 +647,8 @@ static void qt2_close(struct usb_serial_port *port)
/* get the device private data */
port_extra = qt2_get_port_private(port); /* port private data */
/* to check we have successfully flushed the buffers on the hardware,
* we set the flags indicating flushes have occured to false, then ask
* for flushes to occur, then sit in a timed loop until either we
* get notified back that the flushes have happened (good) or we get
* tired of waiting for the flush to happen and give up (bad).
*/
port_extra->rcv_flush = false;
port_extra->xmit_flush = false;
qt2_box_flush(serial, port->number, QT2_FLUSH_TX); /* flush tx buffer */
qt2_box_flush(serial, port->number, QT2_FLUSH_RX); /* flush rx buffer */
/* now wait for the flags to magically go back to being true */
jift = jiffies + (10 * HZ);
do {
if ((port_extra->rcv_flush == true) &&
(port_extra->xmit_flush == true)) {
dbg("Flush completed");
break;
}
schedule();
} while (jiffies <= jift);
/* we don't need to force flush though the hardware, so we skip using
* qt2_box_flush() here */
/* we can now (and only now) stop reading data */
port_extra->close_pending = true;
@ -672,6 +657,9 @@ static void qt2_close(struct usb_serial_port *port)
* still be pushing characters out over the line, so we have to
* wait testing the actual line status until the lines change
* indicating that the data is done transfering. */
/* FIXME: slow this polling down so it doesn't run the USB bus flat out
* if it actually has to spend any time in this loop (which it normally
* doesn't because the buffer is nearly empty) */
jift = jiffies + (10 * HZ); /* 10 sec timeout */
do {
status = qt2_box_get_register(serial, port->number,
@ -848,16 +836,12 @@ static int qt2_chars_in_buffer(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
/* parent usb_serial_port pointer */
int chars = 0;
struct quatech2_port *port_extra; /* extra data for this port */
port_extra = qt2_get_port_private(port);
dbg("%s(): port %d", __func__, port->number);
if ((port->write_urb->status == -EINPROGRESS) &&
(port_extra->tx_pending_bytes != 0))
chars = port->write_urb->transfer_buffer_length;
dbg("%s(): returns %d", __func__, chars);
return chars;
dbg("%s(): port %d: chars_in_buffer = %d", __func__,
port->number, port_extra->tx_pending_bytes);
return port_extra->tx_pending_bytes;
}
/* called when userspace does an ioctl() on the device. Note that
@ -879,7 +863,6 @@ static int qt2_ioctl(struct tty_struct *tty, struct file *file,
/* Declare a wait queue named "wait" */
unsigned int value;
int status;
unsigned int UartNumber;
if (serial == NULL)