openwrtv4/target/linux/brcm2708/patches-4.9/950-0087-amba_pl011-Don-t-use-DT-aliases-for-numbering.patch

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From b34475b447c7e97fa9c4a854849f6e856fe59931 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Tue, 23 Feb 2016 17:26:48 +0000
Subject: [PATCH] amba_pl011: Don't use DT aliases for numbering
The pl011 driver looks for DT aliases of the form "serial<n>",
and if found uses <n> as the device ID. This can cause
/dev/ttyAMA0 to become /dev/ttyAMA1, which is confusing if the
other serial port is provided by the 8250 driver which doesn't
use the same logic.
---
drivers/tty/serial/amba-pl011.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2446,7 +2446,12 @@ static int pl011_setup_port(struct devic
if (IS_ERR(base))
return PTR_ERR(base);
+ /* Don't use DT serial<n> aliases - it causes the device to
+ be renumbered to ttyAMA1 if it is the second serial port in the
+ system, even though the other one is ttyS0. The 8250 driver
+ doesn't use this logic, so always remains ttyS0.
index = pl011_probe_dt_alias(index, dev);
+ */
uap->old_cr = 0;
uap->port.dev = dev;