From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Date: Sat, 31 Jan 2015 04:17:34 +0000 Subject: Re: [PATCH] ARM: shmobile: alt dts: Drop console= bootargs parameter Message-Id: <20150131041731.GA7605@verge.net.au> List-Id: References: <1415075018-27529-1-git-send-email-horms+renesas@verge.net.au> <54CBFC63.4070808@cogentembedded.com> In-Reply-To: <54CBFC63.4070808@cogentembedded.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org Hi Sergei, On Sat, Jan 31, 2015 at 12:49:23AM +0300, Sergei Shtylyov wrote: > Hello. > > On 11/04/2014 07:23 AM, Simon Horman wrote: > > >Alt is booted from DT, so chosen/stdout-path is > >always used, and we can drop the "console=" parameter from chosen/bootargs. > > >This change has a side-effect of changing the console speed from 38400 > >to 115200. This is intentional as 115200 is consistently used on > >all other shmobile boards. > > I'd say it's not very practical to change the console's baud rate from > U-Boot's default It is consistent with the handling of all other boards with renesas SoCs that are present in mainline. > (AFAIR changing baud rate in U-Boot didn't work)... Perhaps that relates to the version of built of uboot. On the board I have access to I see: ver=U-Boot 2013.01.01-g5df9446 (Oct 01 2014 - 14:59:23) And the following setting altered the baud rate of u-boot (IIRC). baudrate5200 > >Cc: Ulrich Hecht > >Cc: Geert Uytterhoeven > >Cc: devicetree@vger.kernel.org > >Signed-off-by: Simon Horman > >--- > > arch/arm/boot/dts/r8a7794-alt.dts | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > >diff --git a/arch/arm/boot/dts/r8a7794-alt.dts b/arch/arm/boot/dts/r8a7794-alt.dts > >index 8aec512..f2cf757 100644 > >--- a/arch/arm/boot/dts/r8a7794-alt.dts > >+++ b/arch/arm/boot/dts/r8a7794-alt.dts > >@@ -20,7 +20,7 @@ > > }; > > > > chosen { > >- bootargs = "console=ttySC0,38400 ignore_loglevel rw root=/dev/nfs ip=dhcp"; > >+ bootargs = "ignore_loglevel rw root=/dev/nfs ip=dhcp"; > > Hm, does this even work as intended? I've tried to boot another R8A7794 > based board and I couldn't get any output with alike command line. Booting > with 'earlyprintk=serial' has shown that tty0 was enabled as a console which > is not what we wanted. If you are backporting this change then I believe it has some dependencies that I can follow up on if it is useful to you. If you are using mainline (e.g. next or renesas-next) then yes, it works. I have tested it numerous times since the patch was merged.