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Commit 479e9b94 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

serial: Refactor uart_flush_buffer() from uart_close() 



In the context of the final tty & port close, flushing the tx
ring buffer after the hardware has already been shutdown and
the ring buffer freed is neither required nor desirable.

uart_flush_buffer() performs 3 operations:
1. Resets tx ring buffer indices, but the tx ring buffer has
   already been freed and the indices are reset if the port is
   re-opened.
2. Calls uart driver's flush_buffer() method
   5 in-tree uart drivers define flush_buffer() methods:
     amba-pl011, atmel-serial, imx, serial-tegra, timbuart
   These have been refactored into the shutdown() method, if
   required.
3. Kicks the ldisc for more writing, but this is undesirable.
   The file handle is being released; any waiting writer will
   will be kicked out by tty_release() with a warning. Further,
   the N_TTY ldisc may generate SIGIO for a file handle which
   is no longer valid.

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 86c80a8e

drivers/tty/serial/amba-pl011.c

+1 −0
Original line number Diff line number Diff line
@@ -1689,6 +1689,7 @@ static void pl011_shutdown(struct uart_port *port) 
			plat->exit();

	}



	pl011_dma_flush_buffer(port);

}



static void

drivers/tty/serial/atmel_serial.c

+15 −13
Original line number Diff line number Diff line
@@ -1801,6 +1801,20 @@ static int atmel_startup(struct uart_port *port) 
	return retval;

}



/*

 * Flush any TX data submitted for DMA. Called when the TX circular

 * buffer is reset.

 */

static void atmel_flush_buffer(struct uart_port *port)

{

	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);



	if (atmel_use_pdc_tx(port)) {

		UART_PUT_TCR(port, 0);

		atmel_port->pdc_tx.ofs = 0;

	}

}



/*

 * Disable the port

 */
@@ -1852,20 +1866,8 @@ static void atmel_shutdown(struct uart_port *port) 
	atmel_free_gpio_irq(port);



	atmel_port->ms_irq_enabled = false;

}



/*

 * Flush any TX data submitted for DMA. Called when the TX circular

 * buffer is reset.

 */

static void atmel_flush_buffer(struct uart_port *port)

{

	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);



	if (atmel_use_pdc_tx(port)) {

		UART_PUT_TCR(port, 0);

		atmel_port->pdc_tx.ofs = 0;

	}

	atmel_flush_buffer(port);

}



/*

drivers/tty/serial/serial-tegra.c

+16 −14
Original line number Diff line number Diff line
@@ -1034,6 +1034,20 @@ static int tegra_uart_startup(struct uart_port *u) 
	return ret;

}



/*

 * Flush any TX data submitted for DMA and PIO. Called when the

 * TX circular buffer is reset.

 */

static void tegra_uart_flush_buffer(struct uart_port *u)

{

	struct tegra_uart_port *tup = to_tegra_uport(u);



	tup->tx_bytes = 0;

	if (tup->tx_dma_chan)

		dmaengine_terminate_all(tup->tx_dma_chan);

	return;

}



static void tegra_uart_shutdown(struct uart_port *u)

{

	struct tegra_uart_port *tup = to_tegra_uport(u);
@@ -1046,6 +1060,8 @@ static void tegra_uart_shutdown(struct uart_port *u) 
	tegra_uart_dma_channel_free(tup, true);

	tegra_uart_dma_channel_free(tup, false);

	free_irq(u->irq, tup);



	tegra_uart_flush_buffer(u);

}



static void tegra_uart_enable_ms(struct uart_port *u)
@@ -1174,20 +1190,6 @@ static void tegra_uart_set_termios(struct uart_port *u, 
	return;

}



/*

 * Flush any TX data submitted for DMA and PIO. Called when the

 * TX circular buffer is reset.

 */

static void tegra_uart_flush_buffer(struct uart_port *u)

{

	struct tegra_uart_port *tup = to_tegra_uport(u);



	tup->tx_bytes = 0;

	if (tup->tx_dma_chan)

		dmaengine_terminate_all(tup->tx_dma_chan);

	return;

}



static const char *tegra_uart_type(struct uart_port *u)

{

	return TEGRA_UART_TYPE;

drivers/tty/serial/serial_core.c

+0 −1
Original line number Diff line number Diff line
@@ -1361,7 +1361,6 @@ static void uart_close(struct tty_struct *tty, struct file *filp) 


	mutex_lock(&port->mutex);

	uart_shutdown(tty, state);

	uart_flush_buffer(tty);



	tty_ldisc_flush(tty);

drivers/tty/serial/timbuart.c

+2 −0
Original line number Diff line number Diff line
@@ -273,6 +273,8 @@ static void timbuart_shutdown(struct uart_port *port) 
	dev_dbg(port->dev, "%s\n", __func__);

	free_irq(port->irq, uart);

	iowrite32(0, port->membase + TIMBUART_IER);



	timbuart_flush_buffer(port);

}



static int get_bindex(int baud)