serial: omap_8250: Fix RTS handling
The OMAP3 UART ignores MCR[1] (ie., UART_MCR_RTS) when in autoRTS
mode (UPF_HARD_FLOW + CRTSCTS). This makes it impossible for either
the serial core or userspace to manually flow control the sender.
Disable autoRTS mode when RTS is lowered and restore the previous
mode when RTS is raised.
Note that the OMAP3 UART provides no mechanism for switching from
autoRTS mode without corrupting incoming data; to access the
necessary register, the line control settings must be set to 8-e-2
and thus any data received during that time will be interpreted with
those settings. This corruption has been observed in practice.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index e02acf0..245b959 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -126,6 +126,7 @@
extern void serial8250_do_shutdown(struct uart_port *port);
extern void serial8250_do_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate);
+extern void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
extern int fsl8250_handle_irq(struct uart_port *port);
int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr);