[U-Boot] [PATCH] ppc: Unlock cache-as-ram in a consistent manner

[Liu Dave-R63238]

> >>> with this patch, this mpc8313 board does this:
> >>>
> >>> U-Boot 2009.06-00524-g28958b8 (Jul 23 2009 - 18:33:11) MPC83XX
> >>>
> >>> Reset Status:
> >>>
> >>> CPU:   e300c3, MPC8313E, Rev: 1.0 at 333.333 MHz, CSB: 166.667 MHz
> >>> Board: Freescale MPC8313ERDB
> >>> I2C:   ready
> >>> DRAM:  128 MB
> >>> FLASH: ## Unknown FLASH on Bank 1 - Size = 0x00000000 = 0 MB
> >>> *** failed ***
> >>> ### ERROR ### Please RESET the board ###
> >>>
> >>> and when reverted, it boots normally, so the board wants to 
> >> agree that
> >>> this patch is reverted.
> >> Flash is mapped cacheable on 8313erdb (and some other 83xx 
> >> boards) -- it
> >> shares a BAT with the locked cache area.
> > 
> > Yes. Scott is right.
> > The rootcause is the classic PPC has not enough BAT.
> 
> 8313erdb has an unused BAT7 (not counting the ones that would 
> normally 
> be used for PCI2), and there are other 83xx boards that look 
> like they get it right.

I believe the 8313erdb is ported from 8349emds.
The 8349emds, itx has same problem as 8313erdb.

We disable the MMU when we use the PCI express in current code.
I remember we had to diable the MMU due to no enough BAT to
cover PCI and PCI express and so on.

Thanks, Dave