The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f3040983132bf3477acd45d2452a906e67c2fec9 Mon Sep 17 00:00:00 2001

From: Razvan Stefanescu razvan.stefanescu@microchip.com Date: Tue, 19 Mar 2019 15:20:34 +0200 Subject: [PATCH] tty/serial: atmel: Add is_half_duplex helper

Use a helper function to check that a port needs to use half duplex communication, replacing several occurrences of multi-line bit checking.

Fixes: b389f173aaa1 ("tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done") Cc: stable stable@vger.kernel.org Signed-off-by: Razvan Stefanescu razvan.stefanescu@microchip.com Acked-by: Richard Genoud richard.genoud@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 41b728d223d1..55ca3416113f 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -231,6 +231,13 @@ static inline void atmel_uart_write_char(struct uart_port *port, u8 value) __raw_writeb(value, port->membase + ATMEL_US_THR); }

+static inline int atmel_uart_is_half_duplex(struct uart_port *port) +{ + return ((port->rs485.flags & SER_RS485_ENABLED) && + !(port->rs485.flags & SER_RS485_RX_DURING_TX)) || + (port->iso7816.flags & SER_ISO7816_ENABLED); +} + #ifdef CONFIG_SERIAL_ATMEL_PDC static bool atmel_use_pdc_rx(struct uart_port *port) { @@ -608,10 +615,9 @@ static void atmel_stop_tx(struct uart_port *port) /* Disable interrupts */ atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);

- if (((port->rs485.flags & SER_RS485_ENABLED) && - !(port->rs485.flags & SER_RS485_RX_DURING_TX)) || - port->iso7816.flags & SER_ISO7816_ENABLED) + if (atmel_uart_is_half_duplex(port)) atmel_start_rx(port); + }

/* @@ -628,9 +634,7 @@ static void atmel_start_tx(struct uart_port *port) return;

if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port)) - if (((port->rs485.flags & SER_RS485_ENABLED) && - !(port->rs485.flags & SER_RS485_RX_DURING_TX)) || - port->iso7816.flags & SER_ISO7816_ENABLED) + if (atmel_uart_is_half_duplex(port)) atmel_stop_rx(port);

if (atmel_use_pdc_tx(port)) @@ -928,9 +932,7 @@ static void atmel_complete_tx_dma(void *arg) */ if (!uart_circ_empty(xmit)) atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx); - else if (((port->rs485.flags & SER_RS485_ENABLED) && - !(port->rs485.flags & SER_RS485_RX_DURING_TX)) || - port->iso7816.flags & SER_ISO7816_ENABLED) { + else if (atmel_uart_is_half_duplex(port)) { /* DMA done, stop TX, start RX for RS485 */ atmel_start_rx(port); } @@ -1512,9 +1514,7 @@ static void atmel_tx_pdc(struct uart_port *port) atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask); } else { - if (((port->rs485.flags & SER_RS485_ENABLED) && - !(port->rs485.flags & SER_RS485_RX_DURING_TX)) || - port->iso7816.flags & SER_ISO7816_ENABLED) { + if (atmel_uart_is_half_duplex(port)) { /* DMA done, stop TX, start RX for RS485 */ atmel_start_rx(port); }