[U-Boot] [PATCH 1/3] arm: spl: Fix SPL booting for OMAP3

[Stefan Roese]

Hi Albert,

On 20.06.2013 18:42, Albert ARIBAUD wrote:
>> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
>> index a9657d1..b05f66a 100644
>> --- a/arch/arm/lib/crt0.S
>> +++ b/arch/arm/lib/crt0.S
>> @@ -85,7 +85,13 @@ ENTRY(_main)
>>  	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
>>  	sub	sp, #GD_SIZE	/* allocate one GD above SP */
>>  	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
>> +#if !defined(CONFIG_SPL_BUILD)
>> +/*
>> + * SPL already has GD set to the correct location (in s_init), we mustn't
>> + * move it around now since some data (clocks etc) is already present.
>> + */
>>  	mov	r8, sp		/* GD is above SP */
>> +#endif
>>  	mov	r0, #0
>>  	bl	board_init_f
>>  
> 
> NAK in this form. I don't want gd to be set "somewhere in the code"
> depending on the actual target; I want it set in crt0.S, period.
> 
> I see there are several locations in ARM architecture or board code
> which set up GD themselves in the same manner as OMAP does. Luckily all
> these locations set it to the same value, the address of gdata.
> 
> The correct fix (read: the one I won't NAK) is thus to add a #else
> clause in the code above, in which r8 will be set to =gdata, and to
> remove the corresponding assignments in the various places where they
> reside.

Here's the problem. Setting r8 in _main is too late. As it has already
been used (in the current implementation) to store some data (e.g.
clocks for baudrate generation etc). Here the code from
arch/arm/cpu/armv7/omap3/board.c:s_init():

#ifdef CONFIG_SPL_BUILD
	gd = &gdata;

	preloader_console_init();

	timer_init();
#endif

Note that this is done *before* _main() is called (we are talking about
SPL for OMAP here). And it did cost me quite some time to find this
problem, that r8 was re-configured in _main() and all the already set
values disappeared again (no serial output etc).

Yes, this needs some cleanup/fixup. Unfortunately I won't find the time
to look into such a cleanup in the next days. Perhaps somebody else
might jump in...

Thanks,
Stefan