[U-Boot] [PATCH] added autodetect of sdram size and nr of banks for ixp

[Martijn de Gouw]

Hi 

> > > > +#ifdef CFG_SDR_CONFIG
> > > >  	mov	r1, #CFG_SDR_CONFIG
> > > > +	mov	r9, #0xff
> > > > +#else
> > > > +	mov	r1, #0x1d /* 256 MB, two banks of 128 MB */
> > > > +	mov	r9, #0
> > > > +#endif
> > >
> > > I don't want such $ifdef's in global code. Why do you 
> thinkthat 2 x
> > > 128 MB would be a default configuration for all IXP based boards?
> >
> > When CFG_SDR_CONFIG is defined, it holds the memory size, 
> which is set
> > in the config.h
> > When this value is not set, autodetection is assumed.
> > Setting up the board as 2 x 128Mb is used for the autodetection.
> 
> Understood. Nevertheless the resulting code is quite complex 
> hard to read.

Not complex, just hard to read because of assembly :)

> 
> > > > +sdr_init:
> >
> > /* snip */
> >
> > > > +sdr_init_done:
> > >
> > > This whole test makes not much sense to me. I think the 
> code should be
> > > changed to use the standard get_ram_size() funciton instead (see
> > > common/memsize.c).
> >
> > get_ram_size will nog set the memory controller to the correct size.
> > The ixp can not run C code when memory is not initialized.
> 
> Because of the missing C environment (stack etc)? We could 
> probably use a part 
> of the QueueManager SRAM for a temorary initial stack, so 
> that we could run C 
> code very early. And do the SDRAM initialization and 
> autodetection in C 
> instead of assembler (as done for PPC).

This would involve a large change in the code, compared to this patch.
Even the relocation code is in assembler right now (because of this
reason)
 
> If we could run this SDRAM setup code in C, you could 
> implement a weak default 
> init function that could be overwritten by a board specific 
> version (in your 

Yes, ofcource, in C life is much simpler.

> case). This way we wouldn't add more custom stuff into the 
> common/generic 
> source files.
> 
> What do you think? 

I think that this code could be used as generic code, it is not board
specific code.
I could change de ifdef structure to enable/disable the autodetection
part, instead of using the CFG_SDR_CONFIG define, but a ifdef would
remain.

> 
> > Maybe it could be used as a replacement for the code in pdnb.c yes.
> 
> Yes. This should be replaced.

Ok, makes sense.

Regards, Martijn de Gouw

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