[PATCH V2 0/4] clk: mvebu: Improve clock drift
Jason Cooper
jason at lakedaemon.net
Wed Sep 3 10:11:41 PDT 2014
On Wed, Sep 03, 2014 at 10:03:39AM -0700, Mike Turquette wrote:
> Quoting Leigh Brown (2014-09-03 07:40:56)
> > On 2014-09-02 09:15, Gregory CLEMENT wrote:
> > > Few users reported a timer drift on the Armada 370 based board such as
> > > the mirabox or the Netgear ReadyNAS 102. This is the second series
> > > with few improvements after the review of the 1st version.
> > >
> > > The reason is that when the SSCG (Spread Spectrum Clock Generator) is
> > > enabled, it shifts the frequency of the clock. The percentage is no
> > > more than 1% but when the clock is used for a timer it leads to a
> > > clock drift.
> > >
> > > This series allows to correct the affected clock when the SSCG is
> > > enabled. This drift can happen on all the mvebu SoC on the cpu clock
> > > block (ie cpu, ddr and l2 cache). Currently the only notable effect is
> > > for the Armada 370 because this SoC use the l2cache clock as source
> > > for the timer. That's why even if the series allow any of the mvebu
> > > SoC to benefit to this correction, Armada 370 is the only user of it.
> > >
> > > The first 2 patches should go through the clk subsystem, whereas the
> > > third one should go to the arm-soc through the mvebu tree.
> > >
> > > The last one is just to fix a typo I found while I was reading the clk
> > > code.
> >
> > This is working superbly for me on my Mirabox, and ntpd is now
> > completely stable.
> >
> > Tested-by: Leigh Brown <leigh at solinno.co.uk>
> >
>
> Clock patches look good to me.
Ok, I'll pull it together into a clock branch and so forth.
thx,
Jason.
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