[PATCH] sunxi: dts: add a note that memory size is adjusted by boot loader.

[Ian Campbell]

On Fri, 2014-01-24 at 16:31 +0100, Hans de Goede wrote:
> Hi,
> 
> On 01/24/2014 03:14 PM, Ian Campbell wrote:
> > I had to spend a couple of minutes proving to myself that this was the case on
> > cubietruck, so add a comment to save the next guy some effort.
> 
> Seems like a good idea to me, one small nitpick though see comments inline.
> 
> > Signed-off-by: Ian Campbell <ijc at hellion.org.uk>
> > Cc: Maxime Ripard <maxime.ripard at free-electrons.com>
> > Cc: Hans de Goede <hdegoede at redhat.com>
> > Cc: linux-arm-kernel at lists.infradead.org
> > Cc: linux-sunxi at googlegroups.com
> > ---
> > This patch applies cleanly against v3.13 and Hans' sunxi-devel branch.
> >
> > A plausible alternative would be to pull the memory node out of the dtsi files
> > and into the board specific files. I didn't go straight to that since I'd have
> > to research all the various boards ;-)
> 
> That won't help, some boards ie the original cubieboard and the mele-a1000 come
> in both 512 MB and 1024 MB versions, and I don't think we want to start maintaining
> 2 different dts files just for that.

I didn't mean to suggest that u-boot should stop updating the dtb, so
e.g. I would have put a 512MB reg in the cubieboard dts, with a similar
comment.

But in cases where there is only one variant (e.g. the cubietruck) I'd
have put a 2GB reg and no comment, even though u-boot would in reality
rewrite the 2GB there. 

> > diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
> > index 3e60883..9ba0beb 100644
> > --- a/arch/arm/boot/dts/sun4i-a10.dtsi
> > +++ b/arch/arm/boot/dts/sun4i-a10.dtsi
> > @@ -30,6 +30,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 1GB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x80000000>;
> >   	};
> >
> 
> The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
> datasheet claims as max RAM.

Oops, I must have missed that.

> 
> > diff --git a/arch/arm/boot/dts/sun5i-a10s.dtsi b/arch/arm/boot/dts/sun5i-a10s.dtsi
> > index 0376c50..d12ed7e 100644
> > --- a/arch/arm/boot/dts/sun5i-a10s.dtsi
> > +++ b/arch/arm/boot/dts/sun5i-a10s.dtsi
> > @@ -27,6 +27,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 512MB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x20000000>;
> >   	};
> >
> 
> This seems wrong (copy paste from A13 error) I've a10s boards with 1G, and the data
> sheet claims 2GB max RAM.

I had expected these values to contain the minimum -- i.e. the one which
would work everywhere, so it would work if for some reason u-boot wasn't
updating correctly. Better to boot with only some of the RAM than to
crash randomly.

> > diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
> > index 907cfcc..658e74b 100644
> > --- a/arch/arm/boot/dts/sun7i-a20.dtsi
> > +++ b/arch/arm/boot/dts/sun7i-a20.dtsi
> > @@ -38,6 +38,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 1GB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x80000000>;
> >   	};
> 
> The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
> datasheet claims as max RAM.

Huh, that's the second time I got the wrong one, and I swear I was
paying attention to it as well!

Ian.