Hello.

On 02/03/2015 03:41 AM, Simon Horman wrote:

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Alt is booted from DT, so chosen/stdout-path is
always used, and we can drop the "console=" parameter from chosen/bootargs.

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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.

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    I'd say it's not very practical to change the console's baud rate from
U-Boot's default

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It is consistent with the handling of all other boards with
renesas SoCs that are present in mainline.

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    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.

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(AFAIR changing baud rate in U-Boot didn't work)...

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    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).

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Perhaps that relates to the version of built of uboot.
On the board I have access to I see:

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ver=U-Boot 2013.01.01-g5df9446 (Oct 01 2014 - 14:59:23)

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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.

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And the following setting altered the baud rate of u-boot (IIRC).

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baudrate=115200

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    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. :-(

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Cc: Ulrich Hecht <redacted>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: devicetree at vger.kernel.org
Signed-off-by: Simon Horman <redacted>
---
  arch/arm/boot/dts/r8a7794-alt.dts | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

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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";

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    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.

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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.

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    Contrariwise, I'm forward-porting.

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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.

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    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