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serial: Refactor uart_flush_buffer() from uart_close()

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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   is no longer valid.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: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2014-10-16 16:54:18 -04:00 committed by Greg Kroah-Hartman
parent 86c80a8e2a
commit 479e9b94fd
5 changed files with 34 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/tty/serial/amba-pl011.c
View File

@ -1689,6 +1689,7 @@ static void pl011_shutdown(struct uart_port *port)
plat->exit();
}
pl011_dma_flush_buffer(port);
}
static void

28
drivers/tty/serial/atmel_serial.c
View File

@ -1801,6 +1801,20 @@ free_irq:
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);
}
/*

30
drivers/tty/serial/serial-tegra.c
View File

@ -1034,6 +1034,20 @@ fail_rx_dma:
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;

1
drivers/tty/serial/serial_core.c
View File

@ -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);

2
drivers/tty/serial/timbuart.c
View File

@ -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)