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authorYinghai Lu <Yinghai.Lu@Sun.COM>2007-07-15 23:37:25 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:34 -0700
commit79492689e40d4f4d3d8a7262781d56fb295b4b86 (patch)
treef66255875725b87a986300735db7fe0212415695 /drivers/serial
parent23936cc0b5d89619c34c2dab11d8cf3d6f7ca028 (diff)
serial: assert DTR for serial console devices
Some RS-232 devices require DTR to be asserted before they can be used. DTR is normally asserted in uart_startup() when the port is opened. But we don't actually open serial console ports, so assert DTR when the port is added. BTW: earlyprintk and early_uart are hard coded to set DTR/RTS. rmk says The only issue I can think of is the possibility for an attached modem to auto-answer or maybe even auto-dial before the system is ready for it to do so. Might have an undesirable cost implication for some running with such a setup. Apart from that, I can't think of any other side effect of this specific patch. Signed-off-by: Yinghai Lu <yinghai.lu@sun.com> Acked-by: Russell King <rmk@arm.linux.org.uk> Cc: Andi Kleen <ak@suse.de> Cc: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Gerd Hoffmann <kraxel@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/serial')
-rw-r--r--drivers/serial/serial_core.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 326020f86f7..9c57486c2e7 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1910,6 +1910,12 @@ uart_set_options(struct uart_port *port, struct console *co,
if (flow == 'r')
termios.c_cflag |= CRTSCTS;
+ /*
+ * some uarts on other side don't support no flow control.
+ * So we set * DTR in host uart to make them happy
+ */
+ port->mctrl |= TIOCM_DTR;
+
port->ops->set_termios(port, &termios, NULL);
co->cflag = termios.c_cflag;