Re: Problems with 2430 NAND prefetch engine

[Tony Lindgren <tony@atomide.com>]

* Juha Kuikka <juha.kuikka@gmail.com> [080408 17:33]:
> Hi,
> 
> I am trying to use the NAND prefetch engine to speed up NAND access.
> 
> In GPMC CS0 is the NAND chip. GPMC_CONFIG7_0 is set to 0x0000084c by
> u-boot. Hence the address for this CS should be 0x0C000000.
> Documentation indicates that the FIFO should be accessible in any
> associated chip-select region after the engine has been enabled.
> 
> In linux I use ioremap() to map 0x0C000000 and use the returned
> pointer to access the prefetch engine FIFO.
> 
> Prefetch engine is configured and started.
> I get FIFOEVENT interrupt from it and try to read the fifo by using
> this ioremap's pointer but kernel crashes with:
> 
> Unhandled fault: external abort on non-linefetch (0x008) at 0xc4854000
> 0xc4854000 corresponds to the pointer ioremap() returned.
>
> Apparently I miss something either in HW or kernel but I cannot think
> of anything.
> Conventional access to the NAND chip through COMMAND/ADDRESS/DATA
> registers works ok.
> Any ideas would be appreciated.

Are you sure you have all the needed clocks on at this point? At least
gpmc_fck should be checked. Of course if access to gpmc works in
general, this is not the problem.

Tony