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

Tony Lindgren tony at atomide.com
Thu Aug 17 17:48:21 CEST 2017


* Matthijs van Duin <matthijsvanduin at gmail.com> [170817 07:56]:
> On 17 August 2017 at 16:49, Matthijs van Duin <matthijsvanduin at gmail.com> wrote:
> > On 17 August 2017 at 15:38, Michael Mrozek <EvilDragon at openpandora.org> wrote:
> >> * The timings are DIFFERENT when running with 400MHz (DDR3-800) and
> >> often not in the datasheets.
> >
> > The datasheet of the RAM does specify the timings to be used for
> > DDR3-800, and we are using them. These timings are also the same as
> > for the single-rank ram.
> 
> Ignore me, I wasn't awake yet. I was confusing the pyra with the
> beaglebone I think :-/
> 
> I think you can mostly get away with using DDR3-1066 parameters at 400
> MHz, although it would unnecessarily slow. A few parameters need to be
> adjusted however, like the max time a row is allowed to be open
> (tRAS_max) and the refresh interval.

We have omap_ddr_clk() return 531840000 in u-boot, so not 400 MHz.
But since the current timings work at 1.42V, I don't see why they
would need to be tweaked for 1.35V.

Regards,

Tony


More information about the Letux-kernel mailing list