[U-Boot] Question about baud rate

[U-Boot] Question about baud rate

[djantzen]

Hi,

I'm using a board similar to canyonlands with a ppc460ex. The baud rate 
for ttyS0 is set to 115200 by the console= bootarg, but I'd also like to 
set ttyS1-3 to 115200 also.

For each of the three uarts, the device tree has the following line:

current-speed = <0>; /* Filled in by U-Boot */

How do I go about configuring u-boot to fill these with the baud rate I 
choose?

Sorry for the silly question!

Thanks,
Dan

[U-Boot] Question about baud rate

[Detlev Zundel]

Hi Dan,

> I'm using a board similar to canyonlands with a ppc460ex. The baud rate 
> for ttyS0 is set to 115200 by the console= bootarg, but I'd also like to 
> set ttyS1-3 to 115200 also.

Why doe you want to setup this parameters "from the outside"?  Really
only the serial device used for a console needs to be setup by
firmware.  All other serial devices should be initialized by the user
space programs using them.

> For each of the three uarts, the device tree has the following line:
>
> current-speed = <0>; /* Filled in by U-Boot */

Checking current U-Boot code, I believe this comment is simply wrong.  I
cannot see any part in the canyonlands / or generic 4xx infrastructure
that fixes up these properties.  Maybe Stefan can comment on this
though.

> How do I go about configuring u-boot to fill these with the baud rate I 
> choose?
>
> Sorry for the silly question!

I don;t think its a silly question, but I also think that you do not
need the configuration ;)

Cheers
  Detlev

-- 
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[U-Boot] Question about baud rate

[djantzen]

> Why doe you want to setup this parameters "from the outside"?  Really
> only the serial device used for a console needs to be setup by
> firmware.  All other serial devices should be initialized by the user
> space programs using them.

I would like my startup script to cat messages to ttyS1, as well as to 
the console (ttyS0). Basically for the purpose of informing users that 
the firmware cannot execute for some reason (we don't like to give 
access to the console). I was trying to avoid including stty or 
setserial, but if this is the accepted way to configure the serial port 
it's not a big deal ;-)

>> For each of the three uarts, the device tree has the following line:
>>
>> current-speed = <0>; /* Filled in by U-Boot */
>
> Checking current U-Boot code, I believe this comment is simply wrong. 
> I
> cannot see any part in the canyonlands / or generic 4xx 
> infrastructure
> that fixes up these properties.  Maybe Stefan can comment on this
> though.
>

Interesting...I also tried manually entering a value here, but it 
didn't seem to have any effect. Maybe it just isn't used?

>> Sorry for the silly question!
>
> I don;t think its a silly question, but I also think that you do not
> need the configuration ;)
>
> Cheers
>   Detlev

Thanks for your response!

Regards,
Dan

[U-Boot] Question about baud rate

[Detlev Zundel]

Hi Dan,

>> Why doe you want to setup this parameters "from the outside"?  Really
>> only the serial device used for a console needs to be setup by
>> firmware.  All other serial devices should be initialized by the user
>> space programs using them.
>
> I would like my startup script to cat messages to ttyS1, as well as to
> the console (ttyS0). Basically for the purpose of informing users that
> the firmware cannot execute for some reason (we don't like to give
> access to the console). I was trying to avoid including stty or
> setserial, but if this is the accepted way to configure the serial
> port it's not a big deal ;-)

Personally I believe that every software task should setup as much as
possible from what it knows to be needed for its own work.  For a serial
program this includes setting the baud rate and the communications
parameter like 8/n/1.

>>> For each of the three uarts, the device tree has the following line:
>>>
>>> current-speed = <0>; /* Filled in by U-Boot */
>>
>> Checking current U-Boot code, I believe this comment is simply
>> wrong. I
>> cannot see any part in the canyonlands / or generic 4xx
>> infrastructure
>> that fixes up these properties.  Maybe Stefan can comment on this
>> though.
>>
>
> Interesting...I also tried manually entering a value here, but it
> didn't seem to have any effect. Maybe it just isn't used?

This may very well be the case.  An answer can probably be found on the
linux ppc mailing list[1] ;)

>>> Sorry for the silly question!
>>
>> I don;t think its a silly question, but I also think that you do not
>> need the configuration ;)
>>
>> Cheers
>>   Detlev
>
> Thanks for your response!

You're welcome!
  Detlev

[1] http://dir.gmane.org/gmane.linux.ports.ppc64.devel
    "PowerPC developers ML" <linuxppc-dev@ozlabs.org>

-- 
Every time history repeats itself the price goes up.
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DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de