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Commit 4833960e authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: mos7840: remove broken chase implementation 



Remove broken "chase" implementation which was supposed to be used to
drain the write buffers at break.

The chase implementation slept on a wait queue which was never woken up
(i.e. no hardware buffers were queried), and thus amounted to nothing
more than polling chars_in_buffer, something which has already been
taken care of by the tty layer.

Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0fce06da

drivers/usb/serial/mos7840.c

+0 −48
Original line number Diff line number Diff line
@@ -218,7 +218,6 @@ struct moschip_port { 
	__u8 shadowMCR;		/* last MCR value received */

	char open;

	char open_ports;

	wait_queue_head_t wait_chase;	/* for handling sleeping while waiting for chase to finish */

	struct usb_serial_port *port;	/* loop back to the owner of this object */



	/* Offsets */
@@ -1092,9 +1091,6 @@ static int mos7840_open(struct tty_struct *tty, struct usb_serial_port *port) 
		mos7840_port->read_urb_busy = false;

	}



	/* initialize our wait queues */

	init_waitqueue_head(&mos7840_port->wait_chase);



	/* initialize our port settings */

	/* Must set to enable ints! */

	mos7840_port->shadowMCR = MCR_MASTER_IE;
@@ -1211,47 +1207,6 @@ static void mos7840_close(struct usb_serial_port *port) 
	mos7840_port->open = 0;

}



/************************************************************************

 *

 * mos7840_block_until_chase_response

 *

 *	This function will block the close until one of the following:

 *		1. Response to our Chase comes from mos7840

 *		2. A timeout of 10 seconds without activity has expired

 *		   (1K of mos7840 data @ 2400 baud ==> 4 sec to empty)

 *

 ************************************************************************/



static void mos7840_block_until_chase_response(struct tty_struct *tty,

					struct moschip_port *mos7840_port)

{

	int timeout = msecs_to_jiffies(1000);

	int wait = 10;

	int count;



	while (1) {

		count = mos7840_chars_in_buffer(tty);



		/* Check for Buffer status */

		if (count <= 0)

			return;



		/* Block the thread for a while */

		interruptible_sleep_on_timeout(&mos7840_port->wait_chase,

					       timeout);

		/* No activity.. count down section */

		wait--;

		if (wait == 0) {

			dev_dbg(&mos7840_port->port->dev, "%s - TIMEOUT\n", __func__);

			return;

		} else {

			/* Reset timeout value back to seconds */

			wait = 10;

		}

	}



}



/*****************************************************************************

 * mos7840_break

 *	this function sends a break to the port
@@ -1275,9 +1230,6 @@ static void mos7840_break(struct tty_struct *tty, int break_state) 
	if (mos7840_port == NULL)

		return;



	/* flush and block until tx is empty */

	mos7840_block_until_chase_response(tty, mos7840_port);



	if (break_state == -1)

		data = mos7840_port->shadowLCR | LCR_SET_BREAK;

	else