[PATCH] ARM: mvebu: use 0xf1000000 as internal registers on Armada 370 DB

[Arnd Bergmann]

On Thursday 02 April 2015 15:36:50 Thomas Petazzoni wrote:
> 
> On Thu, 02 Apr 2015 15:28:09 +0200, Arnd Bergmann wrote:
> 
> > I think it would be better to add a new .dts file that includes the
> > former, and give it a new name, such as armada-370-db-broken-uboot.dts.
> > 
> > We should not stop supporting the older versions, and it would be better
> > to revert the bootloader change in their u-boot before it spreads too far.
> 
> Sorry, but I don't follow you.
> 
> What was wrong was the initial choice in U-Boot made to keep internal
> registers at 0xd0000000. Having the registers at 0xf1000000 is what
> should have been done from the beginning: it is the right thing to do,
> and there is absolutely no reason to do a revert a go back to
> 0xd0000000.
> 
> Actually, having internal registers at 0xd0000000 is a very bad choice,
> as it means that more space in the 0 -> 4 GB physical space is devoted
> to I/O, which overlaps with RAM when you have 4+ GB of RAM. One of the
> reason with moving the registers at 0xf1000000 is to be able to use as
> much RAM as possible.

This device has 1GB, doing an incompatible change to an existing machine
is completely moronic. How hard can it be to special-case this board
in u-boot?

> Also, the proposed change is exactly the same we've done on several
> Marvell evaluation boards in the past:
> 
>   http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts/armada-xp-gp.dts?id=91ed32200e6ea1df19df01355c5c7747f9014102
>   http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts/armada-xp-db.dts?id=82066bdb5a759ec00c18f9667853c4fe8840e83d

I'm aware of those, I just wish they would learn from their mistakes.

> Those boards are evaluation boards from Marvell, only available to
> selected customers, who are supposed to know what they are doing. And
> all of those customers are getting boards with a new version of the
> bootloader that remaps registers at 0xf1000000.
>
> So the patch I'm proposing is simply fixing the kernel so that it works
> for the customers who have access to this Armada 370 DB board.
> 
> If you want a file named armada-370-db-broken-uboot.dts, then it should
> be the one using the 0xd0000000 register address. We can do that if you
> like it, but this .dts file will just be useless clutter as nobody will
> ever use it.

Find a different name then, but don't change the value in the existing
file. It's been around for too long now. The other ones were changed
shortly after being introduced, but anybody who is using
armada-370-db.dts today obviously has the old boot loader and cannot
update the bootloader without breaking their kernels, but they should
at least be able to update their kernels without changing the
scripts.

	Arnd