Re: Uart set up in PBL

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Renaud,

On 04.03.21 17:41, Barbier, Renaud wrote:
>>> Would it possible from the PBL to read the "baudrate" variable from the
>> environment?
>>
>> Normally, you would want to avoid doing anything, but the
>> bare minimum from PBL. Does the baudrate device parameter
>> work for you?
>>
> [Barbier, Renaud] 
> Just to give you a bit more context. In our platform ARM (all non-pbl) or PPC, we add a call to do a PBIT memory test before starting barebox. The uart is initialized just before that at a fixed baud rate of  9600 bauds. Now we have a requirement to support more than one baud rate configurable by the user. And our next ARM based board is going to have a PBL.
> 
> Are you saying that from the PBL, I can do something like baud=getenv("baudrate") to get the environment variable value. This would require to have /dev/env0 instantiated, would not it?

I am saying: don't do it from PBL at all if possible.

> Does not that require to have the environment init code (fs support and all) be compiled as part of the PBL (lwl-y +=....).
> My environment variables are in QSPI, so I would think I could parse the environment variable without the whole barebox support instead.
> If not possible then I think we can find some other way to retrieve the baud rate.

So you load pbl/bare init barebox into SRAM, run PBIT memory test on DRAM,
then extract/copy barebox proper to DRAM or how does it work?

Cheers,
Ahmad


> 
> Cheers.
> 
> 
>> Cheers,
>> Ahmad
>>
>>>
>>> Cheers,
>>> Renaud
>>>
>>>
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