> The Home Hub 2B has both nand and nor flash connected to the ebu, plus 
> an ath9k pci wireless card, and the main difficulty is getting all three
> working at the same time without interfering with each other. The nand 
> driver currently in trunk works fine, provided that open-drain is 
> enabled on the ebu cs1 pin, and provided that wireless is off. However, 
> the only way to get the nor chip to work reliably seems to be disable 
> open-drain on ebu cs1, at which point the nand driver generates jffs2 
> errors. Regardless whether open-drain is enabled or not, switching on 
> wireless also causes jffs2 errors.

Based on my experience with the boards with NOR only, the EBU_CS1 pin
should always be driven (i.e., not open-drain) for the flash not to get
corrupted by PCI. If it is not driven, it takes some time for the pin to
be pulled up (depending on the pull-up resistors), and the flash chip
may still be enabled when the PCI transfers start.

As far as I can see, the problem here is that for two flash chips you
need two chip select signals. IIRC, the EBU always uses GPIO23
(EBU_CS1), no matter whether you use NAND or NOR. So you likely need
another GPIO to select between NAND and NOR, which you have to toggle
manually. Does the original firmware have access to both NAND and NOR
simultaneously? Or does the original bootloader disable NOR before
booting the firmware?

Matti Laakso
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