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Date:   Sat, 05 Dec 2020 07:54:48 +0000
To:     Krzysztof Kozlowski <krzk@kernel.org>
From:   Timon Baetz <timon.baetz@protonmail.com>
Cc:     Sebastian Reichel <sre@kernel.org>,
        Chanwoo Choi <cw00.choi@samsung.com>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kukjin Kim <kgene@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        ~postmarketos/upstreaming@lists.sr.ht
Reply-To: Timon Baetz <timon.baetz@protonmail.com>
Subject: Re: [PATCH 2/3] power: supply: max8997_charger: Set CHARGER current limit
Message-ID: <20201205085442.6ef557fc.timon.baetz@protonmail.com>
In-Reply-To: <20201202215057.GA135888@kozik-lap>
References: <20201202203516.43053-1-timon.baetz@protonmail.com> <20201202203516.43053-2-timon.baetz@protonmail.com> <20201202215057.GA135888@kozik-lap>
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On Wed, 2 Dec 2020 23:50:57 +0200, Krzysztof Kozlowski wrote:
> On Wed, Dec 02, 2020 at 09:07:19PM +0000, Timon Baetz wrote:
> > Register for extcon notification and set charging current depending on
> > the detected cable type. Current values are taken from i9100 kernel
> > fork.
> >
> > Enable and disable the CHARGER regulator based on extcon events and
> > remove regulator-always-on from the device tree.
> >
> > Signed-off-by: Timon Baetz <timon.baetz@protonmail.com>
> > ---
> >  arch/arm/boot/dts/exynos4210-i9100.dts |  1 -
> >  drivers/power/supply/max8997_charger.c | 92 ++++++++++++++++++++++++++
> >  2 files changed, 92 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/boot/dts/exynos4210-i9100.dts b/arch/arm/boot/dts=
/exynos4210-i9100.dts
> > index 6d0c04d77a39..9f8d927e0d21 100644
> > --- a/arch/arm/boot/dts/exynos4210-i9100.dts
> > +++ b/arch/arm/boot/dts/exynos4210-i9100.dts
> > @@ -560,7 +560,6 @@ charger_reg: CHARGER {
> >  =09=09=09=09regulator-name =3D "CHARGER";
> >  =09=09=09=09regulator-min-microamp =3D <60000>;
> >  =09=09=09=09regulator-max-microamp =3D <2580000>;
> > -=09=09=09=09regulator-always-on; =20
>=20
> Thanks for the patch.
>=20
> The DTS changes always go separately.
>=20
> >  =09=09=09};
> >
> >  =09=09=09chargercv_reg: CHARGER_CV {
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/sup=
ply/max8997_charger.c
> > index 1947af25879a..26cd271576ec 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -6,6 +6,7 @@
> >  //  MyungJoo Ham <myungjoo.ham@samsung.com>
> >
> >  #include <linux/err.h>
> > +#include <linux/extcon.h>
> >  #include <linux/module.h>
> >  #include <linux/slab.h>
> >  #include <linux/platform_device.h>
> > @@ -31,6 +32,12 @@ struct charger_data {
> >  =09struct device *dev;
> >  =09struct max8997_dev *iodev;
> >  =09struct power_supply *battery;
> > +=09struct regulator *reg; =20
>=20
> You need to include regulator consumer.h.
>=20
> > +=09struct { =20
>=20
> It makes all dereferences longer. Just add a comment that these are
> related to the extcon.
>=20
> > +=09=09struct extcon_dev *edev;
> > +=09=09struct notifier_block nb;
> > +=09=09struct work_struct work;
> > +=09} extcon;
> >  };
> >
> >  static enum power_supply_property max8997_battery_props[] =3D {
> > @@ -88,6 +95,63 @@ static int max8997_battery_get_property(struct power=
_supply *psy,
> >  =09return 0;
> >  }
> >
> > +static void max8997_battery_extcon_evt_stop_work(void *data)
> > +{
> > +=09struct charger_data *charger =3D data;
> > +
> > +=09cancel_work_sync(&charger->extcon.work);
> > +}
> > +
> > +static void max8997_battery_extcon_evt_worker(struct work_struct *work=
)
> > +{
> > +=09struct charger_data *charger =3D
> > +=09    container_of(work, struct charger_data, extcon.work);
> > +=09int ret, current_limit;
> > +=09struct extcon_dev *edev =3D charger->extcon.edev;
> > + =20
>=20
> It would be useful to report the current with POWER_SUPPLY_PROP_* but
> it is a different patch.
>=20
> > +=09if (extcon_get_state(edev, EXTCON_CHG_USB_SDP) > 0) {
> > +=09=09dev_dbg(charger->dev, "USB SDP charger is connected\n");
> > +=09=09current_limit =3D 450000;
> > +=09} else if (extcon_get_state(edev, EXTCON_CHG_USB_DCP) > 0) {
> > +=09=09dev_dbg(charger->dev, "USB DCP charger is connected\n");
> > +=09=09current_limit =3D 650000;
> > +=09} else if (extcon_get_state(edev, EXTCON_CHG_USB_FAST) > 0) {
> > +=09=09dev_dbg(charger->dev, "USB FAST charger is connected\n");
> > +=09=09current_limit =3D 650000;
> > +=09} else if (extcon_get_state(edev, EXTCON_CHG_USB_SLOW) > 0) {
> > +=09=09dev_dbg(charger->dev, "USB SLOW charger is connected\n");
> > +=09=09current_limit =3D 650000; =20
>=20
> The charger provides 500 mA, so I wonder whether 650 here is correct. Is
> it at different voltage?
>=20

I was wondering about that as well but as far as I can tell
https://github.com/krzk/linux-vendor-backup/blob/samsung/galaxy-s2-epic-4g-=
touch-sph-d710-exynos4210-dump/drivers/misc/max8997-muic.c#L1675-L1678
treats all 4 charger types as MUIC_CHG_TYPE_TA which ends up settings
650 mA. Voltage doesn't seem to change in vendor kernel. =20

> > +=09} else if (extcon_get_state(edev, EXTCON_CHG_USB_CDP) > 0) {
> > +=09=09dev_dbg(charger->dev, "USB CDP charger is connected\n");
> > +=09=09current_limit =3D 650000;
> > +=09} else {
> > +=09=09dev_dbg(charger->dev, "USB charger is diconnected\n");
> > +=09=09current_limit =3D -1;
> > +=09}
> > +
> > +=09if (current_limit > 0) { =20
>=20
> ret should be declared here.
>=20
> > +=09=09ret =3D regulator_set_current_limit(charger->reg, current_limit,=
 current_limit);
> > +=09=09if (ret)
> > +=09=09=09dev_err(charger->dev, "failed to set current limit: %d\n", re=
t); =20
>=20
> Failure of setting the current should rather disable the charging.
>=20
> > +=09=09ret =3D regulator_enable(charger->reg);
> > +=09=09if (ret)
> > +=09=09=09dev_err(charger->dev, "failed to enable regulator: %d\n", ret=
);
> > +=09} else { =20
>=20
> ret should be declared here.
>=20
> > +=09=09ret =3D regulator_disable(charger->reg);
> > +=09=09if (ret)
> > +=09=09=09dev_err(charger->dev, "failed to disable regulator: %d\n", re=
t);
> > +=09} =20
>=20
> What about top-off charging?
>=20
> > +}
> > +
> > +static int max8997_battery_extcon_evt(struct notifier_block *nb,
> > +=09=09=09=09unsigned long event, void *param)
> > +{
> > +=09struct charger_data *charger =3D
> > +=09=09container_of(nb, struct charger_data, extcon.nb);
> > +=09schedule_work(&charger->extcon.work);
> > +=09return NOTIFY_OK;
> > +}
> > +
> >  static const struct power_supply_desc max8997_battery_desc =3D {
> >  =09.name=09=09=3D "max8997_pmic",
> >  =09.type=09=09=3D POWER_SUPPLY_TYPE_BATTERY,
> > @@ -104,6 +168,7 @@ static int max8997_battery_probe(struct platform_de=
vice *pdev)
> >  =09struct i2c_client *i2c =3D iodev->i2c;
> >  =09struct max8997_platform_data *pdata =3D iodev->pdata;
> >  =09struct power_supply_config psy_cfg =3D {};
> > +=09struct extcon_dev *edev;
> >
> >  =09if (!pdata) {
> >  =09=09dev_err(&pdev->dev, "No platform data supplied.\n");
> > @@ -151,6 +216,12 @@ static int max8997_battery_probe(struct platform_d=
evice *pdev)
> >  =09=09return ret;
> >  =09}
> >
> > +=09edev =3D extcon_get_extcon_dev("max8997-muic"); =20
>=20
> Store it directly under charger->edev.
>=20
> > +=09if (edev =3D=3D NULL) { =20
>=20
> if (!edev) {
>=20
> > +=09=09dev_info(&pdev->dev, "extcon is not ready, probe deferred\n"); =
=20
>=20
> Do not print anything on deferrals.
>=20
> > +=09=09return -EPROBE_DEFER;
> > +=09}
> > +
> >  =09charger =3D devm_kzalloc(&pdev->dev, sizeof(*charger), GFP_KERNEL);
> >  =09if (!charger)
> >  =09=09return -ENOMEM;
> > @@ -170,6 +241,27 @@ static int max8997_battery_probe(struct platform_d=
evice *pdev)
> >  =09=09return PTR_ERR(charger->battery);
> >  =09}
> >
> > +=09charger->reg =3D regulator_get(&pdev->dev, "CHARGER"); =20
>=20
> Here and in extcon_get_extcon_dev() - you make all these devices tightly
> coupled. It will work, but I am afraid it's easy to break later.
>=20
> Instead you should have a device node in DTS to which the charger could
> bind and where the driver will find regulator supply and extcon
> phandles (with extcon_get_edev_by_phandle() for example).
>=20
> > +=09if (IS_ERR(charger->reg)) {
> > +=09=09dev_err(&pdev->dev, "couldn't get CHARGER regulator\n");
> > +=09=09return PTR_ERR(charger->reg);
> > +=09}
> > +
> > +=09INIT_WORK(&charger->extcon.work, max8997_battery_extcon_evt_worker)=
;
> > +=09ret =3D devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop=
_work, charger);
> > +=09if (ret) {
> > +=09=09dev_err(&pdev->dev, "failed to add extcon evt stop action: %d\n"=
, ret); =20
>=20
> Missing regulator_put() here and in other places. Use devm-().
>=20
> > +=09=09return ret;
> > +=09}
> > +=09charger->extcon.edev =3D edev;
> > +=09charger->extcon.nb.notifier_call =3D max8997_battery_extcon_evt;
> > +=09ret =3D devm_extcon_register_notifier_all(&pdev->dev, charger->extc=
on.edev,
> > +=09=09=09&charger->extcon.nb); =20
>=20
> Align the arguments with opening '('.
>=20
> Best regards,
> Krzysztof