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.
Richard Ash
Signed-off-by: Richard Ash <richard@xxxxxxxxxxxxxxxx>
---
Index: linux/drivers/staging/quatech_usb2/quatech_usb2.c
===================================================================
--- linux.orig/drivers/staging/quatech_usb2/quatech_usb2.c
+++ linux/drivers/staging/quatech_usb2/quatech_usb2.c
@@ -619,7 +619,10 @@ int qt2_open(struct tty_struct *tty, str
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_
/* 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_
* 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 tt
{
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 *
/* Declare a wait queue named "wait" */
unsigned int value;
- int status;
unsigned int UartNumber;
if (serial == NULL)
--
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