[RFC] Add .dts file for Netgear ReadyNAS 102

[ezequiel.garcia@free-electrons.com (Ezequiel Garcia)]

Hi guys,

I feel I might share some of my findings when I worked on this,
in the hope it's useful for anyone.

On Wed, Jul 03, 2013 at 12:09:36AM +0200, Willy Tarreau wrote:
> > 
> > Which matches what Thomas wrote in a previous email regarding pwa3xx
> > base. 
> 
> Yes and indeed I must say that when I read the driver I found some
> similarities with pxa3xx, though it was done differently. I initially
> wanted to try to merge them but of course without the spec it's a huge
> waste of time, especially considering that this is still in the roadmap
> of the Free Electrons guys even though low priority.
> 

I wish I could say I'm going to work on this soon but, as Thomas said,
we have no idea when/if NAND will be prioritized.

On the other side if you look at the driver Willy just posted, merging
the juicy stuff into pxa3xx-nand driver is not for the faint of heart.

Without the spec, is only tougher.

Just a quick hint. As far as I can recall, one of the first items in a
TODO list should be:

 * adding bigger page support to pxa3xx (4 KiB, 8 KiB).
   Willy's posted driver might be helpful to accomplish this;
   provided your eyes don't melt when you look at it :-)

 * once the above is done, bad block management can/should be added.

With these two we're almost there for R/W support.

> Since I'm now flashing a rootfs from within u-boot, support for the
> NAND is of less importance to me than what it used to, but I have no
> problem with helping with my very limited time. I have 3 machines
> with this controller (mirabox, openblocks AX3, and an XP-GP, though

With my latest patches pxa3xx-nand should at least *detect* the NAND
device in XP-GP. Doesn't work for Mirabox, though.

> the AX3 only has NOR IIRC). I can do some tests if you manage to get
> the driver to work again.
> 
> Be very careful when playing with this, the driver expects the partition
> table to be passed from u-boot as "armada_nand", and if it uses the wrong
> partition layout, you can be certain that ubifs will destroy them at the
> first mount attempt. That's how I initially bricked my mirabox and did so
> repeatedly. Better keep a copy before booting the patched kernel!
> 
> Another point, I had to add a new entry for the Micro 8Gb flash of the
> mirabox, maybe you won't need it or maybe you'll need a different one.
> 

Just a note about this. You need that entry because your driver doesn't
support ONFI-detected flash devices. You could workaround that, by
adding support simple command. I did it for pxa3xx-nand recently:

"mtd: nand: pxa3xx: Add address support for READID command"
http://permalink.gmane.org/gmane.linux.drivers.mtd/46606

Thanks,
-- 
Ezequiel Garc?a, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com