Commit f01a0bd8 authored Mar 09, 2015 by Peter Hurley Committed by Greg Kroah-Hartman Mar 26, 2015

serial: 8250: Check UART_SCR is writable



Au1x00/RT2800+ doesn't implement the 8250 scratch register (and
this may be true of other h/w currently supported by the 8250 driver);
read back the canary value written to the scratch register to enable
the console h/w restart after resume from system suspend.

Fixes: 4516d50a ("serial: 8250: Use canary to restart console ...")
Reported-by: Mason <slash.tmp@free.fr>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 509cb7dc

drivers/tty/serial/8250/8250_core.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -3585,6 +3585,7 @@ void serial8250_suspend_port(int line)
		port->type != PORT_8250) {
		unsigned char canary = 0xa5;
		serial_out(up, UART_SCR, canary);
		if (serial_in(up, UART_SCR) == canary)
		up->canary = canary;
		}

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