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Date:   Thu, 24 Dec 2020 13:13:02 +0000
From:   Timon Baetz <timon.baetz@...tonmail.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Lee Jones <lee.jones@...aro.org>,
        Sebastian Reichel <sre@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v4 4/7] power: supply: max8997_charger: Set CHARGER current limit

On Thu, 24 Dec 2020 10:55:59 +0100, Krzysztof Kozlowski wrote:
> On Wed, Dec 23, 2020 at 01:43:05PM +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@...tonmail.com>
> > ---
> >  drivers/power/supply/max8997_charger.c | 89 ++++++++++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> >
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> > index 1947af25879a..e8532e2af451 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -6,12 +6,14 @@
> >  //  MyungJoo Ham <myungjoo.ham@...sung.com>
> >
> >  #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;
> > +
> > +	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) {
> > +		int 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);
> > +			return;
> > +		}
> > +		ret = regulator_enable(charger->reg);
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to enable regulator: %d\n", ret);
> > +	} else {
> > +		int ret  = regulator_disable(charger->reg);
> > +
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to disable regulator: %d\n", ret);
> > +	}
> > +}
> > +
> > +static int max8997_battery_extcon_evt(struct notifier_block *nb,
> > +				unsigned long event, void *param)
> > +{
> > +	struct charger_data *charger =
> > +		container_of(nb, struct charger_data, extcon_nb);
> > +	schedule_work(&charger->extcon_work);
> > +	return NOTIFY_OK;
> > +}
> > +
> >  static const struct power_supply_desc max8997_battery_desc = {
> >  	.name		= "max8997_pmic",
> >  	.type		= POWER_SUPPLY_TYPE_BATTERY,
> > @@ -170,6 +237,28 @@ static int max8997_battery_probe(struct platform_device *pdev)
> >  		return PTR_ERR(charger->battery);
> >  	}
> >
> > +	charger->reg = devm_regulator_get(&pdev->dev, "charger");  
> 
> Since you do not use get_optional, you will always get a dummy
> regulator. In case of error, you should either print it or entirely fail
> the probe. Silently continuing makes it difficult to spot errors.
> 
> Since the driver could operate in case of extcon/regulator error, just
> dev_err() so failure will be spotted with dmesg.

I will switch to devm_regulator_get_optional() and print an error on 
failure, thanks.

> It will complain on older DTBs because you are introducing incompatible
> change, but that's expected. Just correct all other in-tree DTS.

The other 2 in-tree DTS don't have CHARGER regulators. Not sure
how to correct those. Should I add muic and charger nodes without a
charger-supply? It will still complain in that case.

Thanks for guiding me through this,
Timon

> > +	charger->edev = extcon_get_edev_by_phandle(&pdev->dev, 0);
> > +	if (PTR_ERR(charger->reg) == -EPROBE_DEFER ||
> > +	    PTR_ERR(charger->edev) == -EPROBE_DEFER)
> > +		return -EPROBE_DEFER;
> > +
> > +	if (!IS_ERR(charger->reg) && !IS_ERR(charger->edev)) {
> > +		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
> > +		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
> > +		if (ret) {
> > +			dev_err(&pdev->dev, "failed to add extcon evt stop action: %d\n", ret);
> > +			return ret;
> > +		}
> > +		charger->extcon_nb.notifier_call = max8997_battery_extcon_evt;
> > +		ret = devm_extcon_register_notifier_all(&pdev->dev, charger->edev,
> > +							&charger->extcon_nb);
> > +		if (ret) {
> > +			dev_err(&pdev->dev, "failed to register extcon notifier\n");
> > +			return ret;
> > +		};
> > +	}
> > +
> >  	return 0;
> >  }
> >
> > --
> > 2.25.1
> >
> >  



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