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Message-ID: <430aff196be793003b96fd544f9f64c2eba3ca78.camel@gmail.com>
Subject: Re: [PATCH 1/2] dt-bindings: hwmon: max31827: use supply pin name
From:   Nuno =?ISO-8859-1?Q?S=E1?= <noname.nuno@gmail.com>
To:     Guenter Roeck <linux@roeck-us.net>,
        "Miclaus, Antoniu" <Antoniu.Miclaus@analog.com>
Cc:     Rob Herring <robh@kernel.org>,
        "Matyas, Daniel" <Daniel.Matyas@analog.com>,
        Jean Delvare <jdelvare@suse.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date:   Mon, 25 Sep 2023 08:54:49 +0200
In-Reply-To: <0cb70677-6dfd-43e0-a3c5-cae3b861a7d1@roeck-us.net>
References: <20230921142005.102263-1-antoniu.miclaus@analog.com>
         <20230922211201.GA3600661-robh@kernel.org>
         <CY4PR03MB3399B818487F87D7297EC33F9BFEA@CY4PR03MB3399.namprd03.prod.outlook.com>
         <0cb70677-6dfd-43e0-a3c5-cae3b861a7d1@roeck-us.net>
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On Sun, 2023-09-24 at 05:02 -0700, Guenter Roeck wrote:
> On Sat, Sep 23, 2023 at 02:19:45PM +0000, Miclaus, Antoniu wrote:
> >=20
> >=20
> > > On Thu, Sep 21, 2023 at 05:20:03PM +0300, Antoniu Miclaus wrote:
> > > > The actual hardware pin name for the supply of max31827 is vdd.
> > > > Update the dt-binding to reflect the hardware properties accordingl=
y.
> > >=20
> > > Changing this breaks the ABI. I see the old one wasn't used by the
> > > driver, but that's just one driver potentially. You need some
> > > justification here why it's okay to break the ABI.
> > >=20
> > As I mentioned also in the commit description, the supply should match =
the
> > actual hardware pin name. Otherwise it might create confusion. Usually =
vref
> > refers to an external voltage reference pin used for ADC/DACs which is =
not
> > exactly the case for this part, taking into account that there is no "r=
eference"
> > word mentioned in the datasheet at all. VREF and VDD are usually separa=
te
> > hardware pins. There is a hint indeed in the dts example that the vref-=
supply=20
> > might be referenced to a vdd regulator node, but from my point of view
> > that is not enough. Moreover the current vref-supply is not handled at =
all in
> > the driver, it is only mentioned in the dt-binding (That's why I added =
a second
> > patch in the series handling the supply).
> >=20
> > If the justification is not enough to apply this change, then I can kee=
p only the
> > second patch, which handles the regulator in the driver and use the=C2=
=A0 old `vref`
> > naming which currently appears only in the dt-binding.
> >=20
>=20
> That would have been a good argument when the property was introduced, bu=
t if
> there are any systems with existing bindings out there they will use the =
old
> name and fail after this change is applied.
>=20

How about introducing the new property and add 'deprecated: true' to the ol=
d one. I
guess the second patch would still remain as-is. Or is this just not worth =
the noise?

- Nuno S=C3=A1