Re: [PATCH v2 2/6] power: supply: max8997_charger: Set CHARGER current limit

[Timon Baetz]

On Mon, 21 Dec 2020 15:16:27 +0100, Krzysztof Kozlowski wrote:
> On Mon, Dec 21, 2020 at 09:53:15AM +0000, Timon Baetz wrote:
> > Register for extcon notification and set charging current depending on
> > the detected cable type. Current values are taken from vendor kernel,
> > where most charger types end up setting 650mA [0].
> >
> > Also enable and disable the CHARGER regulator based on extcon events.
> >
> > [0] 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
> >
> > Signed-off-by: Timon Baetz <timon.baetz@xxxxxxxxxxxxxx>
> > ---
> >  drivers/mfd/max8997.c                  |  4 +-
> >  drivers/power/supply/max8997_charger.c | 94 ++++++++++++++++++++++++++
> >  2 files changed, 96 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mfd/max8997.c b/drivers/mfd/max8997.c
> > index 68d8f2b95287..55d3a6f97783 100644
> > --- a/drivers/mfd/max8997.c
> > +++ b/drivers/mfd/max8997.c
> > @@ -29,9 +29,9 @@
> >  static const struct mfd_cell max8997_devs[] = {
> >  	{ .name = "max8997-pmic", },
> >  	{ .name = "max8997-rtc", },
> > -	{ .name = "max8997-battery", },
> > +	{ .name = "max8997-battery", .of_compatible = "maxim,max8997-battery", },
> >  	{ .name = "max8997-haptic", },
> > -	{ .name = "max8997-muic", },
> > +	{ .name = "max8997-muic", .of_compatible = "maxim,max8997-muic", },  
> 
> Undocumented bindings. The checkpatch should complain about it, so I
> assume you did not run it. Please run the checkpatch.
> 
> >  	{ .name = "max8997-led", .id = 1 },
> >  	{ .name = "max8997-led", .id = 2 },
> >  };
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> > index 1947af25879a..6e8750e455ea 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -6,12 +6,14 @@
> >  //  MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> >
> >  #include <linux/err.h>
> > +#include <linux/extcon.h>
> >  #include <linux/module.h>
> >  #include <linux/slab.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/power_supply.h>
> >  #include <linux/mfd/max8997.h>
> >  #include <linux/mfd/max8997-private.h>
> > +#include <linux/regulator/consumer.h>
> >
> >  /* MAX8997_REG_STATUS4 */
> >  #define DCINOK_SHIFT		1
> > @@ -31,6 +33,10 @@ struct charger_data {
> >  	struct device *dev;
> >  	struct max8997_dev *iodev;
> >  	struct power_supply *battery;
> > +	struct regulator *reg;
> > +	struct extcon_dev *edev;
> > +	struct notifier_block extcon_nb;
> > +	struct work_struct extcon_work;
> >  };
> >
> >  static enum power_supply_property max8997_battery_props[] = {
> > @@ -88,6 +94,67 @@ static int max8997_battery_get_property(struct power_supply *psy,
> >  	return 0;
> >  }
> >
> > +static void max8997_battery_extcon_evt_stop_work(void *data)
> > +{
> > +	struct charger_data *charger = data;
> > +
> > +	cancel_work_sync(&charger->extcon_work);
> > +}
> > +
> > +static void max8997_battery_extcon_evt_worker(struct work_struct *work)
> > +{
> > +	struct charger_data *charger =
> > +	    container_of(work, struct charger_data, extcon_work);
> > +	struct extcon_dev *edev = charger->edev;
> > +	int current_limit, ret;
> > +
> > +	if (extcon_get_state(edev, EXTCON_CHG_USB_SDP) > 0) {
> > +		dev_dbg(charger->dev, "USB SDP charger is connected\n");
> > +		current_limit = 450000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_DCP) > 0) {
> > +		dev_dbg(charger->dev, "USB DCP charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_FAST) > 0) {
> > +		dev_dbg(charger->dev, "USB FAST charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_SLOW) > 0) {
> > +		dev_dbg(charger->dev, "USB SLOW charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_CDP) > 0) {
> > +		dev_dbg(charger->dev, "USB CDP charger is connected\n");
> > +		current_limit = 650000;
> > +	} else {
> > +		dev_dbg(charger->dev, "USB charger is diconnected\n");
> > +		current_limit = -1;
> > +	}
> > +
> > +	if (current_limit > 0) {
> > +		ret = regulator_set_current_limit(charger->reg, current_limit, current_limit);
> > +		if (ret) {
> > +			dev_err(charger->dev, "failed to set current limit: %d\n", ret);
> > +			goto regulator_disable;  
> 
> Unusual error path... if regulator was not enabled before and
> regulator_set_current_limit() failed, you disable the regulator? Why?
> Wasn't it already disabled?

Because I thought you asked me to in v1 of this patch:
> Failure of setting the current should rather disable the charging.

I probably misunderstood you comment then. So I guess it should just
return?

Thanks for reviewing,
Timon