From 479e9b94fdce7bc46f669831012fc12f56696fd7 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Thu, 16 Oct 2014 16:54:18 -0400 Subject: [PATCH] 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 Further, the N_TTY ldisc may generate SIGIO for a file handle which is no longer valid.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 Cc: Russell King Cc: Laxman Dewangan Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- 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 02016fcd91b8..8469b66ff832 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1689,6 +1689,7 @@ 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 edde3eca055d..8a84034d130c 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -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); } /* diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c index 53d7c31ce098..78a5cf65bf02 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 1166c52e51f4..787d67f74bd9 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -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); diff --git a/drivers/tty/serial/timbuart.c b/drivers/tty/serial/timbuart.c index 0d11d5032b93..e9e252324fb6 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) -- 2.34.1