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From: jason@lakedaemon.net (Jason Cooper)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V2 0/4] clk: mvebu: Improve clock drift
Date: Wed, 3 Sep 2014 13:11:41 -0400	[thread overview]
Message-ID: <20140903171141.GO30467@titan.lakedaemon.net> (raw)
In-Reply-To: <20140903170339.11368.17168@quantum>

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@solinno.co.uk>
> > 
> 
> Clock patches look good to me.

Ok, I'll pull it together into a clock branch and so forth.

thx,

Jason.

  reply	other threads:[~2014-09-03 17:11 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-02  8:15 [PATCH V2 0/4] clk: mvebu: Improve clock drift Gregory CLEMENT
2014-09-02  8:15 ` [PATCH V2 1/4] clk: mvebu: Fix clk frequency value if SSCG is enabled Gregory CLEMENT
2014-09-02  8:15 ` [PATCH V2 2/4] clk: mvebu: armada-370: Fix timer drift caused by the SSCG deviation Gregory CLEMENT
2014-09-02  8:15 ` [PATCH V2 3/4] ARM: mvebu: add SSCG to Armada 370 Device Tree Gregory CLEMENT
2014-09-02  8:15 ` [PATCH V2 4/4] clk: mvebu: armada-375: Fix the description of the SAR in the comment Gregory CLEMENT
2014-09-03 14:40 ` [PATCH V2 0/4] clk: mvebu: Improve clock drift Leigh Brown
2014-09-03 17:03   ` Mike Turquette
2014-09-03 17:11     ` Jason Cooper [this message]
2014-09-09 15:42 ` Jason Cooper

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