Commit 5dad5c31 authored by Axel Haslam's avatar Axel Haslam Committed by Greg Kroah-Hartman
Browse files

greybus: uart: wait for credits on shutdown 



We should try to wait until all credits are accounted
for before returning from shutdown.

For this purpose add a helper function that will
wait on completion, and call it form the shutdown.
This helper will also be useful when "wait until sent" is
implemented.

Signed-off-by: default avatarAxel Haslam <ahaslam@baylibre.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 2b3b87f0

drivers/staging/greybus/uart.c

+31 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/kdev_t.h>

#include <linux/kfifo.h>

#include <linux/workqueue.h>

#include <linux/completion.h>



#include "greybus.h"

#include "gbphy.h"
@@ -39,6 +40,7 @@ 
#define GB_UART_WRITE_FIFO_SIZE		PAGE_SIZE

#define GB_UART_WRITE_ROOM_MARGIN	1	/* leave some space in fifo */

#define GB_UART_FIRMWARE_CREDITS	4096

#define GB_UART_CREDIT_WAIT_TIMEOUT_MSEC	10000



struct gb_tty_line_coding {

	__le32	rate;
@@ -71,6 +73,7 @@ struct gb_tty { 
	struct kfifo write_fifo;

	bool close_pending;

	unsigned int credits;

	struct completion credits_complete;

};



static struct tty_driver *gb_tty_driver;
@@ -197,6 +200,9 @@ static int gb_uart_receive_credits_handler(struct gb_operation *op) 
	 */

	tty_port_tty_wakeup(&gb_tty->port);



	if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)

		complete(&gb_tty->credits_complete);



	return ret;

}
@@ -317,6 +323,24 @@ static int send_break(struct gb_tty *gb_tty, u8 state) 
				 &request, sizeof(request), NULL, 0);

}



static int gb_uart_wait_for_all_credits(struct gb_tty *gb_tty)

{

	int ret;



	if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)

		return 0;



	ret = wait_for_completion_timeout(&gb_tty->credits_complete,

			msecs_to_jiffies(GB_UART_CREDIT_WAIT_TIMEOUT_MSEC));

	if (!ret) {

		dev_err(&gb_tty->gbphy_dev->dev,

			"time out waiting for credits\n");

		return -ETIMEDOUT;

	}



	return 0;

}



static int gb_uart_flush(struct gb_tty *gb_tty, u8 flags)

{

	struct gb_uart_serial_flush_request request;
@@ -765,12 +789,18 @@ static void gb_tty_port_shutdown(struct tty_port *port) 
	kfifo_reset_out(&gb_tty->write_fifo);

	spin_unlock_irqrestore(&gb_tty->write_lock, flags);



	if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)

		goto out;



	ret = gb_uart_flush(gb_tty, GB_SERIAL_FLAG_FLUSH_TRANSMITTER);

	if (ret) {

		dev_err(&gb_tty->gbphy_dev->dev,

			"error flushing transmitter: %d\n", ret);

	}



	gb_uart_wait_for_all_credits(gb_tty);



out:

	gb_tty->close_pending = false;

}
@@ -842,6 +872,7 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev, 
		goto exit_buf_free;



	gb_tty->credits = GB_UART_FIRMWARE_CREDITS;

	init_completion(&gb_tty->credits_complete);



	minor = alloc_minor(gb_tty);

	if (minor < 0) {

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