[U-Boot] [PATCH 11/14] sunxi: Fill memory before comparing it when doing dram init on sun6i

Ian Campbell
2014-12-22T14:19:20Z

On Fri, 2014-12-19 at 17:55 +0100, Hans de Goede wrote:
> Hi,
>
> On 18-12-14 20:12, Ian Campbell wrote:
> > On Tue, 2014-12-16 at 21:31 +0100, Hans de Goede wrote:
> >> The sun8i boot0 code fills the DRAM with a "random" pattern before comparing
> >> it at different offsets to do columns, etc. detection. The sun6i boot0 code
> >> does not do it, but it seems like a good idea to do this regardless.
> >
> > Is this the right way round?
>
> Yes, while working on the sun8i code I noticed that it was prefilling memory
> before doing wrap-around checks like the sun6i code is doing too, and then I
> realized that the sun6i code was relying on whatever is in DRAM being random
> enough for its wrap-around tests to work, without ensuring it is random
> enough.
>
> > The existing sun6i code (which you are
> > moving here) seems to _rely_ on something having written a useful
> > pattern, which I would have assumed to have been boot0. Or else how does
> > it work now? Chance?
>
> Yep, it purely works by chance so far.

"excellent". Can you mention that in the commit message please. With
that: Acked-by: Ian Campbell <ijc@hellion.org.uk>

Ian.