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

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Message-ID: <20190903173604.GA18177@bogus>
Date:   Tue, 3 Sep 2019 18:36:04 +0100
From:   Rob Herring <robh@...nel.org>
To:     Martin Fuzzey <martin.fuzzey@...wbird.group>
Cc:     Biwen Li <biwen.li@....com>, a.zummo@...ertech.it,
        alexandre.belloni@...tlin.com, mark.rutland@....com,
        leoyang.li@....com, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Martin Fuzzey <mfuzzey@...keon.com>
Subject: Re: [v3,1/2] dt-bindings: rtc: pcf85263/pcf85363: add some properties

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.

> 
> 
> > +- 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
> 
>