From: Shawn Guo <shawnguo@kernel.org>
To: "Y.b. Lu" <yangbo.lu@nxp.com>
Cc: Richard Cochran <richardcochran@gmail.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Leo Li <leoyang.li@nxp.com>
Subject: Re: [PATCH] ARM: dts: ls1021a: output PPS signal on FIPER2
Date: Sun, 17 May 2020 21:54:25 +0800 [thread overview]
Message-ID: <20200517135424.GA25973@dragon> (raw)
In-Reply-To: <AM7PR04MB688584E51D49FD4A7761734DF8BC0@AM7PR04MB6885.eurprd04.prod.outlook.com>
On Thu, May 14, 2020 at 03:13:45AM +0000, Y.b. Lu wrote:
> Hi Shawn,
>
> > -----Original Message-----
> > From: Shawn Guo <shawnguo@kernel.org>
> > Sent: Wednesday, May 13, 2020 4:23 PM
> > To: Y.b. Lu <yangbo.lu@nxp.com>
> > Cc: linux-arm-kernel@lists.infradead.org; Leo Li <leoyang.li@nxp.com>;
> > Richard Cochran <richardcochran@gmail.com>
> > Subject: Re: [PATCH] ARM: dts: ls1021a: output PPS signal on FIPER2
> >
> > On Mon, Apr 27, 2020 at 11:56:55AM +0800, Yangbo Lu wrote:
> > > Output PPS signal on FIPER2 (Fixed Period Interval Pulse)
> > > which is more desired by user.
> > >
> > > Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
> > > ---
> > > arch/arm/boot/dts/ls1021a.dtsi | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm/boot/dts/ls1021a.dtsi b/arch/arm/boot/dts/ls1021a.dtsi
> > > index 760a68c..b2ff27a 100644
> > > --- a/arch/arm/boot/dts/ls1021a.dtsi
> > > +++ b/arch/arm/boot/dts/ls1021a.dtsi
> > > @@ -772,7 +772,7 @@
> > > fsl,tmr-prsc = <2>;
> > > fsl,tmr-add = <0xaaaaaaab>;
> > > fsl,tmr-fiper1 = <999999995>;
> > > - fsl,tmr-fiper2 = <99990>;
> > > + fsl,tmr-fiper2 = <999999995>;
> >
> > Not sure code change matches patch subject and commit log. The change
> > is about changing fsl,tmr-fiper2 setting from one value to another.
>
> The calculation refers to Documentation/devicetree/bindings/ptp/ptp-qoriq.txt. It looks complicated.
> But to be simple, to get 1PPS signal (period is 1s) on FIPER2, the value should be set as,
> fiper2 = <desired period> - <tclk-period> = 1000000000ns - 5ns = 999999995.
Please update commit log to include how new value comes.
Shawn
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next prev parent reply other threads:[~2020-05-17 13:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 3:56 [PATCH] ARM: dts: ls1021a: output PPS signal on FIPER2 Yangbo Lu
2020-05-13 8:22 ` Shawn Guo
2020-05-14 3:13 ` Y.b. Lu
2020-05-17 13:54 ` Shawn Guo [this message]
2020-05-19 2:58 ` Y.b. Lu
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