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

From: Krzysztof Kozlowski <krzk@kernel.org>
To: Timon Baetz <timon.baetz@protonmail.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Lee Jones <lee.jones@linaro.org>,
	Sebastian Reichel <sre@kernel.org>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-pm@vger.kernel.org,
	~postmarketos/upstreaming@lists.sr.ht
Subject: Re: [PATCH v2 2/6] power: supply: max8997_charger: Set CHARGER current limit
Date: Mon, 21 Dec 2020 15:16:27 +0100	[thread overview]
Message-ID: <20201221141627.GB33797@kozik-lap> (raw)
In-Reply-To: <20201221095001.595366-2-timon.baetz@protonmail.com>

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@protonmail.com>
> ---
>  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@samsung.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, 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?

Best regards,
Krzysztof