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Date:   Mon, 01 Feb 2021 09:26:42 +0000
To:     Krzysztof Kozlowski <krzk@kernel.org>
From:   Timon Baetz <timon.baetz@protonmail.com>
Cc:     Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Sebastian Reichel <sre@kernel.org>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-pm@vger.kernel.org
Reply-To: Timon Baetz <timon.baetz@protonmail.com>
Subject: Re: [PATCH 3/3] power: supply: max8997_charger: Switch to new binding
Message-ID: <20210201083128.18499ffd.timon.baetz@protonmail.com>
In-Reply-To: <20210131172840.fxaadhhsafa4aeex@kozik-lap>
References: <20210130172747.2022977-1-timon.baetz@protonmail.com> <20210130172747.2022977-4-timon.baetz@protonmail.com> <20210131172840.fxaadhhsafa4aeex@kozik-lap>
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On Sun, 31 Jan 2021 18:28:40 +0100, Krzysztof Kozlowski wrote:
> On Sat, Jan 30, 2021 at 05:30:14PM +0000, Timon Baetz wrote:
> > Get regulator from parent device's node and extcon by name.
> >
> > Signed-off-by: Timon Baetz <timon.baetz@protonmail.com>
> > ---
> >  drivers/power/supply/max8997_charger.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/sup=
ply/max8997_charger.c
> > index 321bd6b8ee41..625d8cc4312a 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -168,6 +168,7 @@ static int max8997_battery_probe(struct platform_de=
vice *pdev)
> >  =09int ret =3D 0;
> >  =09struct charger_data *charger;
> >  =09struct max8997_dev *iodev =3D dev_get_drvdata(pdev->dev.parent);
> > +=09struct device_node *np =3D pdev->dev.of_node;
> >  =09struct i2c_client *i2c =3D iodev->i2c;
> >  =09struct max8997_platform_data *pdata =3D iodev->pdata;
> >  =09struct power_supply_config psy_cfg =3D {};
> > @@ -237,20 +238,23 @@ static int max8997_battery_probe(struct platform_=
device *pdev)
> >  =09=09return PTR_ERR(charger->battery);
> >  =09}
> >
> > +=09// grab regulator from parent device's node
> > +=09pdev->dev.of_node =3D iodev->dev->of_node;
> >  =09charger->reg =3D devm_regulator_get_optional(&pdev->dev, "charger")=
;
> > +=09pdev->dev.of_node =3D np; =20
>=20
> I think the device does not have its own node anymore. Or did I miss
> something?

The idea is to reset of_node to whatever it was before (NULL) and basically=
=20
leave the device unchanged. Probe might run again because of deferral.

> >  =09if (IS_ERR(charger->reg)) {
> >  =09=09if (PTR_ERR(charger->reg) =3D=3D -EPROBE_DEFER)
> >  =09=09=09return -EPROBE_DEFER;
> >  =09=09dev_info(&pdev->dev, "couldn't get charger regulator\n");
> >  =09}
> > -=09charger->edev =3D extcon_get_edev_by_phandle(&pdev->dev, 0);
> > -=09if (IS_ERR(charger->edev)) {
> > -=09=09if (PTR_ERR(charger->edev) =3D=3D -EPROBE_DEFER)
> > +=09charger->edev =3D extcon_get_extcon_dev("max8997-muic");
> > +=09if (IS_ERR_OR_NULL(charger->edev)) {
> > +=09=09if (!charger->edev) =20
>=20
> Isn't NULL returned when there is simply no extcon? It's different than
> deferred probe. Returning here EPROBE_DEFER might lead to infinite probe
> tries (on every new device probe) instead of just failing it.

extcon_get_extcon_dev() just loops through all registered extcon devices
and compared names. It will return NULL when "max8997-muic" isn't
registered yet. extcon_get_extcon_dev() never returns EPROBE_DEFER so
checking for NULL seems to be the only way. Other drivers using that
function also do NULL check and return EPROBE_DEFER.

Thanks for reviewing,
Timon