linux-kernel - RE: [EXT] Re: [v3,1/2] dt-bindings: rtc: pcf85263/pcf85363: add some properties

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Date:   Tue, 10 Sep 2019 10:21:32 +0000
From:   Biwen Li <biwen.li@....com>
To:     'Rob Herring' <robh@...nel.org>,
        Martin Fuzzey <martin.fuzzey@...wbird.group>
CC:     "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        Leo Li <leoyang.li@....com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Martin Fuzzey <mfuzzey@...keon.com>
Subject: RE: [EXT] Re: [v3,1/2] dt-bindings: rtc: pcf85263/pcf85363: add some
 properties

> Caution: EXT Email
> 
> On Tue, Sep 03, 2019 at 11:37:01AM +0200, Martin Fuzzey wrote:
> > On 03/09/2019 08:18, Biwen Li wrote:
> > > diff --git a/Documentation/devicetree/bindings/rtc/pcf85363.txt
> > > b/Documentation/devicetree/bindings/rtc/pcf85363.txt
> > > index 94adc1cf93d9..588f688b30d1 100644
> > > --- a/Documentation/devicetree/bindings/rtc/pcf85363.txt
> > > +++ b/Documentation/devicetree/bindings/rtc/pcf85363.txt
> > > @@ -8,10 +8,39 @@ Required properties:
> > >   Optional properties:
> > >   - interrupts: IRQ line for the RTC (not implemented).
> > > +- interrupt-output-pin: The interrupt output pin must be
> > > +  "INTA" or "INTB", default value is "INTA"
> > > +
> >
> >
> > The hardware has 2 interrupt pins which can be mapped to various
> > interrupt sources (alarm1, alarm2, periodic, ...)
> >
> > Currently the driver only supports alarm1.
> >
> > It is even possible to use both pins for the same interrupt (eg if
> > INTA were wired to the SoC, INTB to a PMIC and both used for alarm...)
> >
> >
> > So maybe it would be better to have
> >
> > alarm1-interrupt-output-pin: The interrupt output pin used for the
> > alarm function. Must be "INTA", "INTB" or "BOTH"
> 
> That's a property per source. 2 properties possible sources (either a mask or list)
> would be my preference.
> 
> Also, whatever you end up with needs a vendor prefix.
> 
> >
> > Then, if and when other types of interrupts are supported by the
> > driver new properties could be added for them.
> >
> >
> >
> > > +- quartz-load-femtofarads: The internal capacitor to select for the quartz:
> > > +   PCF85263_QUARTZCAP_7pF          [0]
> > > +   PCF85263_QUARTZCAP_6pF          [1]
> > > +   PCF85263_QUARTZCAP_12p5pF       [2] DEFAULT
> > > +
> >
> >
> > The standard DT property "quartz-load-femtofarads" takes the real
> > physical value in femto Farads ie values should be 7000, 6000, 12500 without
> defines.
> 
> I believe I said this on the last version.
Yes, I will fix it in v4.
> 
> >
> >
> > > +- nxp,quartz-drive-strength: Drive strength for the quartz:
> > > +   PCF85263_QUARTZDRIVE_100ko      [0] DEFAULT
> > > +   PCF85263_QUARTZDRIVE_60ko       [1]
> > > +   PCF85263_QUARTZDRIVE_500ko      [2]
> > > +
> >
> >
> > Not sure about this.
> >
> > Wouldn't it be better to either use a real impedence value in ohms
> > (like load property above, even though it is a vendor specific value)
> > rather than a define, or defines for "Low, Medium, High"?
> >
> >
> > Martin
> >
> >