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Commit dba05832 authored by Russell King's avatar Russell King
Browse files

SERIAL: core: add hardware assisted h/w flow control support 



Ports which are handling h/w flow control in hardware must not have
their RTS state altered depending on the tty's hardware-stopped state.
Avoid this additional logic when setting the termios state.

Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 2cbacafd

drivers/tty/serial/serial_core.c

+7 −0
Original line number Diff line number Diff line
@@ -1255,6 +1255,13 @@ static void uart_set_termios(struct tty_struct *tty, 
		uart_set_mctrl(uport, mask);

	}



	/*

	 * If the port is doing h/w assisted flow control, do nothing.

	 * We assume that tty->hw_stopped has never been set.

	 */

	if (uport->flags & UPF_HARD_FLOW)

		return;



	/* Handle turning off CRTSCTS */

	if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {

		spin_lock_irqsave(&uport->lock, flags);

include/linux/serial_core.h

+2 −0
Original line number Diff line number Diff line
@@ -163,6 +163,8 @@ struct uart_port { 
#define UPF_BUGGY_UART		((__force upf_t) (1 << 14))

#define UPF_NO_TXEN_TEST	((__force upf_t) (1 << 15))

#define UPF_MAGIC_MULTIPLIER	((__force upf_t) (1 << 16))

/* Port has hardware-assisted h/w flow control (iow, auto-RTS *not* auto-CTS) */

#define UPF_HARD_FLOW		((__force upf_t) (1 << 21))

/* Port has hardware-assisted s/w flow control */

#define UPF_SOFT_FLOW		((__force upf_t) (1 << 22))

#define UPF_CONS_FLOW		((__force upf_t) (1 << 23))