Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751611AbdITOEr (ORCPT ); Wed, 20 Sep 2017 10:04:47 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:36918 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750892AbdITOEp (ORCPT ); Wed, 20 Sep 2017 10:04:45 -0400 X-Google-Smtp-Source: AOwi7QCJENg1eqaEwn9Ut/Acj4AO6mKpCXRoCtHJepnWPz5jxW5TtPuVLEOMRDj/Nig+/149POxtWg== Date: Wed, 20 Sep 2017 23:04:42 +0900 From: Stafford Horne To: Geert Uytterhoeven Cc: LKML , Openrisc , Rob Herring , Mark Rutland , Jonas Bonn , Stefan Kristiansson , "devicetree@vger.kernel.org" Subject: Re: [PATCH] openrisc: dts: or1ksim: Add stdout-path Message-ID: <20170920140442.GY2609@lianli.shorne-pla.net> References: <20170919140024.32563-1-shorne@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2725 Lines: 85 Hi Geert, On Tue, Sep 19, 2017 at 06:49:48PM +0200, Geert Uytterhoeven wrote: > Hi Stafford, > > On Tue, Sep 19, 2017 at 4:00 PM, Stafford Horne wrote: > > During reviews of the OpenRISC SMP patch series it was suggested to add > > stdout-path to the SMP dts file. Add stdout-path to our other dts files > > to be a good example. > > > > Signed-off-by: Stafford Horne > > --- > > arch/openrisc/boot/dts/or1ksim.dts | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/openrisc/boot/dts/or1ksim.dts b/arch/openrisc/boot/dts/or1ksim.dts > > index 5d4f9027afaf..ecc30968cbcb 100644 > > --- a/arch/openrisc/boot/dts/or1ksim.dts > > +++ b/arch/openrisc/boot/dts/or1ksim.dts > > @@ -7,6 +7,7 @@ > > > > chosen { > > bootargs = "console=uart,mmio,0x90000000,115200"; > > + stdout-path = &serial0; > > I think that should be: > > - bootargs = "console=uart,mmio,0x90000000,115200"; > + stdout-path = "serial0:115200"; > > If stdout-path is present, it will become the default console. > All other UART parameters except for the serial speed are derived from > the serial0 node (= serial@90000000) in DT. Thanks for the tip. I have seen examples using alias `&serial0;` and using the name directly `serio0:115200', but I guess I didnt really understand what was going on. I read through as much of the console initialization, of, earlycon and printk code as I needed to refresh my memory on this... It seems there are a few other issues here: - To use "serial0:115200" we will need an alias to the path (or specify the full path) - It looks like we can't use console= and stdout-path at the same time - We still need "earlycon" to define that we want to initialize early printk I think updating to something like the below works, but its a few extra lines: diff --git a/arch/openrisc/boot/dts/or1ksim.dts b/arch/openrisc/boot/dts/or1ksim.dts index ecc30968cbcb..37779a45947c 100644 --- a/arch/openrisc/boot/dts/or1ksim.dts +++ b/arch/openrisc/boot/dts/or1ksim.dts @@ -5,9 +5,13 @@ #size-cells = <1>; interrupt-parent = <&pic>; + aliases { + uart0 = &serial0; + }; + chosen { - bootargs = "console=uart,mmio,0x90000000,115200"; - stdout-path = &serial0; + bootargs = "earlycon"; + stdout-path = "uart0:115200"; }; memory@0 { The boot prompt before showed: Kernel command line: console=uart,mmio,0x90000000,115200 earlycon: uart0 at MMIO 0x90000000 (options '115200') bootconsole [uart0] enabled Now it shows: Kernel command line: earlycon earlycon: ns16550a0 at MMIO 0x90000000 (options '115200') bootconsole [ns16550a0] enabled -Stafford