[U-Boot-Users] [PATCH] ppc4xx: Don't use last 256 bytes of SDRAM, workaround for 440EPx CHIP 11 errata

Stefan Roese
2008-03-20T10:29:06Z

Hi Wolfgang,

On Thursday 20 March 2008, Wolfgang Denk wrote:
> > This patch adds this workaround for the following 440EPx boards:
> > sequoia, lwmon5. Others should probably follow this example.
>
> OK, the default configs for Sequoia doesn't use shared log buffer, and
> the lwmon5 uses CONFIG_ALT_LB_ADDR (i. e. it puts the log buffer in
> OCM), so these boards will work.
>
> But any changes to the configuration may easily break this again.

Understood.

> I don't like the idea that each affected board has to fix this
> (probably differently) in it's board config file. I would prefer a
> fix (common to all affected boards) in one central location.

I don't like this either. But I have not come up with a "generic" solution
till now. It's not so easy since the 440EPx SDRAM setup code is sometimes
common (cpu/ppc4xx/denali_spd_ddr2.c) and sometimes board specific. And it
gets even more complicated when ECC initialization is needed too. So
currently I have no "better" solution as to do it in a board specific way.

As always, patches implementing a "better" more generic solution are welcome.

Thanks.

Best regards,
Stefan

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