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

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Message-ID: <2374870a-a728-b046-9ec6-bd7773411f50@flowbird.group>
Date:   Tue, 3 Sep 2019 11:37:01 +0200
From:   Martin Fuzzey <martin.fuzzey@...wbird.group>
To:     Biwen Li <biwen.li@....com>, a.zummo@...ertech.it,
        alexandre.belloni@...tlin.com, robh+dt@...nel.org,
        mark.rutland@....com, leoyang.li@....com
Cc:     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 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"

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.


> +- 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