amba_pl011: Don't use DT aliases for numbering

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------

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.
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/tty/serial/amba-pl011.c

@@ -2599,7 +2599,12 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
 	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;