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

From: Krzysztof Kozlowski <[email-masked]>
Date: Mon, 21 Dec 2020 16:43:11 +0100

On Mon, Dec 21, 2020 at 03:35:07PM +0000, Timon Baetz wrote:
> 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 <[email-masked]>
> > > ---
> > >  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 <[email-masked]>
> > >
> > >  #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?

Yes, I was not specific enough. In v1 you enabled the charging even in
case of regulator_set_current_limit() error. Instead, the charging
should not be enabled, so just return here with error.

Best regards,
Krzysztof

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