Re: [PATCH 2/3] power: supply: max8997_charger: Set CHARGER current limit

From: Timon Baetz <timon.baetz@protonmail.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
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
Subject: Re: [PATCH 2/3] power: supply: max8997_charger: Set CHARGER current limit
Date: Sat, 05 Dec 2020 07:54:48 +0000	[thread overview]
Message-ID: <20201205085442.6ef557fc.timon.baetz@protonmail.com> (raw)
In-Reply-To: <20201202215057.GA135888@kozik-lap>

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 {
> >  				regulator-name = "CHARGER";
> >  				regulator-min-microamp = <60000>;
> >  				regulator-max-microamp = <2580000>;
> > -				regulator-always-on;  
> 
> Thanks for the patch.
> 
> The DTS changes always go separately.
> 
> >  			};
> >
> >  			chargercv_reg: CHARGER_CV {
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/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 {
> >  	struct device *dev;
> >  	struct max8997_dev *iodev;
> >  	struct power_supply *battery;
> > +	struct regulator *reg;  
> 
> You need to include regulator consumer.h.
> 
> > +	struct {  
> 
> It makes all dereferences longer. Just add a comment that these are
> related to the extcon.
> 
> > +		struct extcon_dev *edev;
> > +		struct notifier_block nb;
> > +		struct work_struct work;
> > +	} extcon;
> >  };
> >
> >  static enum power_supply_property max8997_battery_props[] = {
> > @@ -88,6 +95,63 @@ 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);
> > +	int ret, current_limit;
> > +	struct extcon_dev *edev = charger->extcon.edev;
> > +  
> 
> It would be useful to report the current with POWER_SUPPLY_PROP_* but
> it is a different patch.
> 
> > +	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;  
> 
> The charger provides 500 mA, so I wonder whether 650 here is correct. Is
> it at different voltage?
> 

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.  

> > +	} 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 should be declared here.
> 
> > +		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);  
> 
> Failure of setting the current should rather disable the charging.
> 
> > +		ret = regulator_enable(charger->reg);
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to enable regulator: %d\n", ret);
> > +	} else {  
> 
> ret should be declared here.
> 
> > +		ret = regulator_disable(charger->reg);
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to disable regulator: %d\n", ret);
> > +	}  
> 
> What about top-off charging?
> 
> > +}
> > +
> > +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,
> > @@ -104,6 +168,7 @@ static int max8997_battery_probe(struct platform_device *pdev)
> >  	struct i2c_client *i2c = iodev->i2c;
> >  	struct max8997_platform_data *pdata = iodev->pdata;
> >  	struct power_supply_config psy_cfg = {};
> > +	struct extcon_dev *edev;
> >
> >  	if (!pdata) {
> >  		dev_err(&pdev->dev, "No platform data supplied.\n");
> > @@ -151,6 +216,12 @@ static int max8997_battery_probe(struct platform_device *pdev)
> >  		return ret;
> >  	}
> >
> > +	edev = extcon_get_extcon_dev("max8997-muic");  
> 
> Store it directly under charger->edev.
> 
> > +	if (edev == NULL) {  
> 
> if (!edev) {
> 
> > +		dev_info(&pdev->dev, "extcon is not ready, probe deferred\n");  
> 
> Do not print anything on deferrals.
> 
> > +		return -EPROBE_DEFER;
> > +	}
> > +
> >  	charger = devm_kzalloc(&pdev->dev, sizeof(*charger), GFP_KERNEL);
> >  	if (!charger)
> >  		return -ENOMEM;
> > @@ -170,6 +241,27 @@ static int max8997_battery_probe(struct platform_device *pdev)
> >  		return PTR_ERR(charger->battery);
> >  	}
> >
> > +	charger->reg = regulator_get(&pdev->dev, "CHARGER");  
> 
> 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.
> 
> 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).
> 
> > +	if (IS_ERR(charger->reg)) {
> > +		dev_err(&pdev->dev, "couldn't get CHARGER regulator\n");
> > +		return PTR_ERR(charger->reg);
> > +	}
> > +
> > +	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);  
> 
> Missing regulator_put() here and in other places. Use devm-().
> 
> > +		return ret;
> > +	}
> > +	charger->extcon.edev = edev;
> > +	charger->extcon.nb.notifier_call = max8997_battery_extcon_evt;
> > +	ret = devm_extcon_register_notifier_all(&pdev->dev, charger->extcon.edev,
> > +			&charger->extcon.nb);  
> 
> Align the arguments with opening '('.
> 
> Best regards,
> Krzysztof