linux-kernel - Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

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Date:   Tue, 4 Apr 2023 14:26:16 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     "Tilki, Ibrahim" <Ibrahim.Tilki@...log.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "Arslanbenzer, Zeynep" <Zeynep.Arslanbenzer@...log.com>
Subject: Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

On 04/04/2023 10:35:53+0000, Tilki, Ibrahim wrote:
> >>>>> +  aux-voltage-chargeable:
> >>>>> +    enum: [0, 1, 2]
> >>>>> +    description: |
> >>>>> +      Enables trickle charger.
> >>>>> +      0: Charger is disabled (default)
> >>>>> +      1: Charger is enabled
> >>>>> +      2: Charger is enabled with a diode
> >>>>
> >>>> 2 is not an allowed value. I asked to drop this property. It is coming
> >>>> from rtc.yaml. I also do not understand "with a diode". So otherwise it
> >>>> is charging with, I don't know, FET?
> >>>
> >>> No, what is not explained here (and maybe not unsterstood by the
> >>> submitter) is that the RTC has an extra diode so, charging will always
> >>> enable a diode, select a resistor and then have or not an extra diode.
> >>> Figure2 of the MAX31329 datasheet is great.
> >>>
> >> 
> >> That is exactly why I had "adi,trickle-diode-enable" property in previous patch.
> >> So if I can't have "adi,trickle-diode-enable" and can't add an additional value
> >> to "aux-voltage-chargeable", I am not sure how to add support for the extra
> >> diode at this point.
> >
> > Ask the person who asked you to remove adi,trickle-diode-enable...
> 
> That was the purpose.
> 

If the earlier submission was clearer my answer would have been
different but note how I had to dig up the datasheet to understand there
were two diodes. All the trickle chargers have a schottky diode so
"adi,trickle-diode-enable" nor the commit log were explicit about the
second diode (which is a regular diode).

aux-voltage-chargeable is enabling a diode on all the existing RTC
drivers so instead of trying to make me look like the bad guy you should
rather thank for taking the time trying to get better DT bindings.


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com