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is no longer valid.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@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Laxman Dewangan <ldewangan@xxxxxxxxxx>
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 1 +
drivers/tty/serial/atmel_serial.c | 2 ++
drivers/tty/serial/serial-tegra.c | 2 ++
drivers/tty/serial/serial_core.c | 1 -
drivers/tty/serial/timbuart.c | 2 ++
5 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index dacf0a0..4255eef 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1676,6 +1676,7 @@ static void pl011_shutdown(struct uart_port *port)
plat->exit();
}
+ pl011_dma_flush_buffer(port);
}
static void
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 53eeea1..8aea441 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1664,6 +1664,8 @@ static void atmel_shutdown(struct uart_port *port)
* Free the interrupt
*/
free_irq(port->irq, port);
+
+ atmel_flush_buffer(port);
}
/*
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index d5c2a28..2f5d699 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -1042,6 +1042,8 @@ 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)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f13a769..212ee07 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1351,7 +1351,6 @@ 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);
diff --git a/drivers/tty/serial/timbuart.c b/drivers/tty/serial/timbuart.c
index f87097a..57d8dc0 100644
--- a/drivers/tty/serial/timbuart.c
+++ b/drivers/tty/serial/timbuart.c
@@ -278,6 +278,8 @@ 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)
--
2.0.0
--
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