linux-kernel - Re: [PATCH 2/2] dt-bindings: rtc: nxp,pcf8563: add hiz-output property

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Message-ID: <202310261021467b56f131@mail.local>
Date:   Thu, 26 Oct 2023 12:21:46 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Javier Carrasco <javier.carrasco@...fvision.net>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: rtc: nxp,pcf8563: add hiz-output
 property

On 26/10/2023 12:13:23+0200, Javier Carrasco wrote:
> I want to model the INTA pin as a clock source that only should run in
> sleep mode because its clock is only used in that mode. Therefore I want
> the pin to stay in hi-Z during normal operation.

Can you disclose what is the user of the clock, do you have a driver for
this device?

> 
> I do not want to get any interrupts from the INTA pin and the battery
> mode indication is not relevant for me either. I do not know the CCF
> mechanism in other RTCs though, but I think that the hi-Z mode
> accomplishes exactly what I described.The assumption about the battery
> mode is therefore beyond my knowledge, but my first reaction is that we
> already have the hi-Z for that.
> 
> So in the end I just need a mechanism to configure INTA as hi-Z, which
> the driver still does not support. There is another application where
> the clock output is not required even though it is physically connected,
> so hi-Z is again an interesting mode and the battery mode would be
> available if it ever becomes relevant for anyone.
> 

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