[Letux-kernel] 2GB vs. 4GB Pyra RAM tests

Michael Mrozek EvilDragon at openpandora.org
Thu Aug 17 15:38:31 CEST 2017


Okay, got some replies from my distributor.
The RAM is tested to work with 1.35V.

He's got some ideas though:

* The timings are DIFFERENT when running with 400MHz (DDR3-800) and
often not in the datasheets. If we're running at that speed, we might
have to adjust those. The timings can be found on the JEDEC
Specification on page 170 and later (I'll send the document to you via
Mail, as that's not public).

* Also, if we're running at low speed, the DLL can interfere with the
RAM. This can be disabled via Mode-Register (might be something we can
try).

* As it's dual rank, it could be the layout needs to be adjusted (as it
has more load on the lines). However, then I guess it would run
unstable at 1.4V as well, wouldn't it?

Anyways, that DLL and the timings are our best guess for now, I think.


-- 
Greetings,

Michael Mrozek

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