[U-Boot] Fixing IXP42x boards - some general questions

[Wolfgang Denk]

Dear Michael Schwingen,

In message <4D13175F.8030207 at discworld.dascon.de> you wrote:
> 
> Startup code. Is the following correct?
>  - code starts from flash, with TEXT_BASE = start of flash, ie. the code
> is linked to flash addresses.

Correct.

>  - DATA/BSS are behind the text segment in flash, so the code may not
> write RAM variables until relocation

Correct.

In addition, BSS is not initialized yet, so you should not even try
reading variables in BSS, as these will contain random data.  This
affects especially static variables that are supposed to be
initialized with zero.

>  - code in flash sets up RAM, copies + relocates u-boot to RAM, and
> continues there

Correct.

> Timer system.
>  - For IXP, there are two variants of the timer system - one using
> interrupts, and one without interrupts. Both do not work currently.
> I have patches that fix the non-interrupt version, changing
> CONFIG_SYS_HZ from 66666666 to 1000, bringing it in line with what most
> other ARM platforms do.

I cannot nomment on this.  Marek?

> What is the preferred way of handling timers? Should CONFIG_SYS_HZ be
> 1000 or rather the timer clock?

CONFIG_SYS_HZ must always be defiend as 1000.

> What about interrupts? Use them or avoid them?

If you can do without interrupts, I would do that, because it's
simpler.

> What about the Intel reference board (IXDP425)? Previously, I used that
> one as a reference on how things should be done, but it looks broken, too.
> I can prepare patches for IXDP425, but I can't currently test them (we
> should have one at work, but that might take some time).

I cannot help with that either.  Marek?

Best regards,

Wolfgang Denk

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