linux-kernel - RE: [PATCH RESEND V2 1/3] clocksource/drivers/sysctr: Add optional clock-frequency property

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Message-ID: <DB3PR0402MB3916D17328CF69C09C74A3D8F5FD0@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Date:   Thu, 27 Jun 2019 13:11:55 +0000
From:   Anson Huang <anson.huang@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        Abel Vesa <abel.vesa@....com>,
        "ccaione@...libre.com" <ccaione@...libre.com>,
        "angus@...ea.ca" <angus@...ea.ca>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "agx@...xcpu.org" <agx@...xcpu.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH RESEND V2 1/3] clocksource/drivers/sysctr: Add optional
 clock-frequency property

Hi, Daniel

> On 23/06/2019 14:38, Anson.Huang@....com wrote:
> > From: Anson Huang <Anson.Huang@....com>
> >
> > Systems which use platform driver model for clock driver require the
> > clock frequency to be supplied via device tree when system counter
> > driver is enabled.
> >
> > This is necessary as in the platform driver model the of_clk
> > operations do not work correctly because system counter driver is
> > initialized in early phase of system boot up, and clock driver using
> > platform driver model is NOT ready at that time, it will cause system
> > counter driver initialization failed.
> >
> > Add the optinal clock-frequency to the device tree bindings of the NXP
> > system counter, so the frequency can be handed in and the of_clk
> > operations can be skipped.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@....com>
> > ---
> > Changes since V1:
> > 	- improve commit log, no content change.
> > ---
> >  Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt | 6
> > ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt
> > b/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt
> > index d576599..c9907a0 100644
> > --- a/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt
> > +++ b/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt
> > @@ -14,6 +14,11 @@ Required properties:
> >  - clocks : 	    Specifies the counter clock.
> >  - clock-names: 	    Specifies the clock's name of this module
> >
> > +Optional properties:
> > +
> > +- clock-frequency : Specifies system counter clock frequency and indicates
> system
> > +		    counter driver to skip clock operations.
> > +
> 
> Shouldn't it be required and mutually exclusive with clocks/clock-names?
>
Yes, make sense, I ever thought about it when doing this patch, but eventually I picked
the optional...will fix it in next version.

Thanks,
Anson

> >  Example:
> >
> >  	system_counter: timer@...a0000 {
> > @@ -22,4 +27,5 @@ Example:
> >  		clocks = <&clk_8m>;
> >  		clock-names = "per";
> >  		interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
> > +		clock-frequency = <8333333>;
> >  	};
> >
> 
>