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

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Date:   Tue, 4 Apr 2023 14:18:24 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Ibrahim Tilki <Ibrahim.Tilki@...log.com>, a.zummo@...ertech.it,
        jdelvare@...e.com, linux@...ck-us.net, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        devicetree@...r.kernel.org,
        Zeynep Arslanbenzer <Zeynep.Arslanbenzer@...log.com>
Subject: Re: [PATCH v5 2/2] dt-bindings: rtc: add max313xx RTCs

On 04/04/2023 12:06:14+0200, Krzysztof Kozlowski wrote:
> On 04/04/2023 11:56, Alexandre Belloni wrote:
> > On 04/04/2023 10:14:33+0200, Krzysztof Kozlowski wrote:
> >> On 04/04/2023 09:44, Alexandre Belloni wrote:
> >>>>
> >>>>> charging will always
> >>>>> enable a diode, select a resistor and then have or not an extra diode.
> >>>>> Figure2 of the MAX31329 datasheet is great.
> >>>>
> >>>> So the diode is in the max313xx? Then why enabling it is a property of
> >>>> DT? Either this should be inferred from compatible or is even a policy,
> >>>> not a DT property. Just because device has a register for something, is
> >>>> not an argument that "something" should be in DT.
> >>>
> >>> Well, it depends on the battery that is installed on the board so it
> >>> makes sense to have it in DT.
> >>
> >> OK, that would be a good reason, but I wonder why? Why choosing diode or
> >> not depends on the battery? Wouldn't you always want to have the diode?
> >>
> > 
> > It limits the maximum current used to charge the battery or supercap to
> > not exceed what is allowed.
> 
> and I still wonder why someone would like to allow exceeding what is
> allowed. IOW, what is the use case to disable the diode?
> 

The battery or supercap is the part defining the current limit. why
would you want to limit the current if you can charge faster?


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