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

Hans de Goede
2014-12-22T15:47:20Z

Hi,

On 22-12-14 15:19, Ian Campbell 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.

Done.

> With that: Acked-by: Ian Campbell <ijc@hellion.org.uk>

Thanks, the now fully acked sun8i support patch-set has been pushed to
u-boot-sunxi/next .

Thanks for all the reviews!

Regards,

Hans