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Date: Thu, 16 Oct 2014 16:54:18 -0400
From: Peter Hurley <peter@...leysoftware.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
Jiri Slaby <jslaby@...e.cz>,
One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Peter Hurley <peter@...leysoftware.com>,
Nicolas Ferre <nicolas.ferre@...el.com>,
Russell King <linux@....linux.org.uk>,
Laxman Dewangan <ldewangan@...dia.com>
Subject: [PATCH -next 01/10] 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is no longer valid.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@...el.com>
Cc: Russell King <linux@....linux.org.uk>
Cc: Laxman Dewangan <ldewangan@...dia.com>
Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
drivers/tty/serial/amba-pl011.c | 1 +
drivers/tty/serial/atmel_serial.c | 28 +++++++++++++++-------------
drivers/tty/serial/serial-tegra.c | 30 ++++++++++++++++--------------
drivers/tty/serial/serial_core.c | 1 -
drivers/tty/serial/timbuart.c | 2 ++
5 files changed, 34 insertions(+), 28 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8572f2a..5b82d7a 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1674,6 +1674,7 @@ 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 d7d4584..8b13d4d 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1801,6 +1801,20 @@ free_irq:
}
/*
+ * 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
*/
static void atmel_shutdown(struct uart_port *port)
@@ -1851,20 +1865,8 @@ 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);
}
/*
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 53d7c31..78a5cf6 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -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;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 221ca6f..ce0e762 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1360,7 +1360,6 @@ 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 0d11d50..e9e2523 100644
--- a/drivers/tty/serial/timbuart.c
+++ b/drivers/tty/serial/timbuart.c
@@ -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)
--
2.1.1
--
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