On Mon, 22 Dec 2014 14:19:20 +0000 Ian Campbell ijc@hellion.org.uk wrote:
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, are you fine with the fact that it still works by chance even after this "fix"? Albeit with a much higher chance of not running into troubles.