[PATCH] ARM: shmobile: alt dts: Drop console= bootargs parameter
Sergei Shtylyov
sergei.shtylyov at cogentembedded.com
Wed Feb 4 14:43:01 PST 2015
Hello.
On 02/03/2015 03:41 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.
>> Well, not quite: Henninger/Porter is still using 38400.
> From my point of view that is an oversight which I would have
> resolved had I ever obtained access to the hardware.
I'll look into that when I have time.
>>>> (AFAIR changing baud rate in U-Boot didn't work)...
>> That was a recollection from the other board though, I haven't yet tried
>> to do it on the SILK board (and I'm unable to currently as the power supply
>> seems dead).
>>> 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)
>> U-Boot 2013.01.01 (Oct 17 2014 - 20:59:18)
> It looks like my version has some extra patches (the g5df9446 bit).
> But I could be reading things wrong.
>>> And the following setting altered the baud rate of u-boot (IIRC).
>>> baudrate=115200
>> I was going to try that but the board just didn't power up.
I have switched to another board now (with newer U-Boot flashed),
and I was able to change the baud rate in U-Boot. However, SPL and U-Boot
still start at 38400 and now I'm having garbage instead of the version and
hardware info. :-(
>>>>> Cc: Ulrich Hecht <ulrich.hecht+renesas at gmail.com>
>>>>> Cc: Geert Uytterhoeven <geert+renesas at glider.be>
>>>>> Cc: devicetree at vger.kernel.org
>>>>> Signed-off-by: Simon Horman <horms+renesas at verge.net.au>
>>>>> ---
>>>>> 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.
The kernel console started working automagically for me at 115200 on the
new board.
>>> 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.
>> Contrariwise, I'm forward-porting.
>>> 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.
>> I'm traditionally using the 'renesas-devel-*' tags.
> If you are using 'renesas-devel-*' tags (and forward porting) then
> you should be in good shape. But if you would like me to verify a particular
> tag I'm happy to do so. It is not unheard of for different instances of
> the same board behave in different ways.
Thank you, looks like there's no need now.
WBR, Sergei
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