[U-Boot] [PATCH v2] arm: cm4008, cm41xx: set gd->ram_size in dram_init

Yann Vernier
2012-07-06T09:14:59Z

On Friday 06 July 2012 10:43:40 you wrote:
> >>> =((CONFIG_SYS_SDRAM_BASE+CONFIG_SYS_SDRAM_SIZE-0x10000)<<(22-16) | \ +
> >>> (CONFIG_SYS_SDRAM_BASE>>(16-12) | 0x00e))
> >>
> >> ugh ... magic. Will it work for every possible setting?
> >> How about one setting CONFIG_SYS_SDRAM_BASE != 0x0? I the base address
> >> related to register content in any way?
> >
> > It's not a guarded secret, although it is far from obvious where to find
> > it. One way is micrel.com - Products - Ethernet ICs / ARM based SOC's -
> > HW Design Kit. Within that zip file,
> > KS8695X_EVAL_HW_RV4.0_DP/RegDescription/KS8695X Register Description
> > v1.1.pdf
>
> With this information I understand your equation. I think you should not
> do it that way. You may solve the current state (all devices have 8
> column, 4 bank and 32 bit). But one adding (well, if that will ever come
> ;) another board with different setting will get in trouble here and
> need to find another solution. Maybe more sophisticated by doing another
> equation.
>
> I think a straight forward solution here would be to add another special
> define in the board config, write the magic number down there and maybe
> describe what the number stands for. You can then just use the
> previously defined value in start.S.
> You may have a look for at91 lowlevel_init, there it is done that way.

I shall. In fact, I may already have this problem as I need to verify the
timing on the flash memory (I have the demo board, not a cm4xxx), and the
reason I work on this is that we may design another board soon.

I'm a little hesitant about how to fit these changes together, though; for now
I have three barely separated patches, but overhauling all those magic numbers
changes them all yet again. These three patches are all necessary to make my
u-boot work in the first place, while fixing the magic values is a code cleanup
change - probably editing arch/arm/include/asm/arch-ks8695/platform.h which
currently contains a few meaningless constants like KS8695_SDRAM_START and a
consistent misspelling of definitions.

Could I save the value decoding and corresponding configuration changes for a
fourth patch?