linux-kernel - Re: [PATCH v4 05/10] power: supply: max77693: Add USB extcon detection for enabling charging

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Message-ID: <bf5350ec-f722-4188-9e10-da5d5cb93e44@kernel.org>
Date: Fri, 16 Aug 2024 12:00:00 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Artur Weber <aweber.kernel@...il.com>,
 Chanwoo Choi <cw00.choi@...sung.com>
Cc: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Lee Jones <lee@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Alim Akhtar <alim.akhtar@...sung.com>, linux-pm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
 ~postmarketos/upstreaming@...ts.sr.ht, Henrik Grimler <henrik@...mler.se>,
 Wolfgang Wiedmeyer <wolfgit@...dmeyer.de>,
 Denis 'GNUtoo' Carikli <GNUtoo@...erdimension.org>
Subject: Re: [PATCH v4 05/10] power: supply: max77693: Add USB extcon
 detection for enabling charging

On 16/08/2024 10:19, Artur Weber wrote:
> 1. Add a function that allows for enabling/disabling charging.
> 
> 2. Add a device tree property, "maxim,usb-connector", that can be used to
> specify a USB connector to use to detect whether a charging cable has
> been plugged in/out, and enable/disable charging accordingly.
> 
> The extcon listener/worker implementation is inspired by the rt5033_charger
> driver.
> 
> Tested-by: Henrik Grimler <henrik@...mler.se>
> Signed-off-by: Artur Weber <aweber.kernel@...il.com>
> ---
> Changes in v4:
> - Fix missing connector property causing probe deferrals
> 

Thank you for your patch. There is something to discuss/improve.


> +static void max77693_charger_extcon_work(struct work_struct *work)
> +{
> +	struct max77693_charger *chg = container_of(work, struct max77693_charger,
> +						  cable.work);
> +	struct extcon_dev *edev = chg->cable.edev;
> +	int connector, state;
> +	int ret;
> +
> +	for (connector = EXTCON_USB_HOST; connector <= EXTCON_CHG_USB_PD;
> +	     connector++) {
> +		state = extcon_get_state(edev, connector);
> +		if (state == 1)
> +			break;
> +	}
> +
> +	switch (connector) {
> +	case EXTCON_CHG_USB_SDP:
> +	case EXTCON_CHG_USB_DCP:
> +	case EXTCON_CHG_USB_CDP:
> +	case EXTCON_CHG_USB_ACA:
> +	case EXTCON_CHG_USB_FAST:
> +	case EXTCON_CHG_USB_SLOW:
> +	case EXTCON_CHG_USB_PD:
> +		ret = max77693_set_charging(chg, true);
> +		if (ret) {
> +			dev_err(chg->dev, "failed to enable charging\n");
> +			break;
> +		}
> +		dev_info(chg->dev, "charging. connector type: %d\n",
> +			 connector);

This and next one should be also dev_dbg. It is completely normal
condition, kind of expected thing to happen, so users do not need to be
bugged every time they plugs cable.

> +		break;
> +	default:
> +		ret = max77693_set_charging(chg, false);
> +		if (ret) {
> +			dev_err(chg->dev, "failed to disable charging\n");
> +			break;
> +		}
> +		dev_info(chg->dev, "not charging. connector type: %d\n",
> +			 connector);
> +		break;
> +	}
> +
> +	power_supply_changed(chg->charger);
> +}
> +
> +static int max77693_charger_extcon_notifier(struct notifier_block *nb,
> +					  unsigned long event, void *param)
> +{
> +	struct max77693_charger *chg = container_of(nb, struct max77693_charger,
> +						    cable.nb);
> +
> +	schedule_work(&chg->cable.work);
> +
> +	return NOTIFY_OK;
> +}
> +
>  /*
>   * Sets charger registers to proper and safe default values.
>   */
> @@ -734,12 +814,34 @@ static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
>  {
>  	struct device_node *np = dev->of_node;
>  	struct power_supply_battery_info *battery_info;
> +	struct device_node *np_conn, *np_edev;
>  
>  	if (!np) {
>  		dev_err(dev, "no charger OF node\n");
>  		return -EINVAL;
>  	}
>  
> +	np_conn = of_parse_phandle(np, "maxim,usb-connector", 0);

Where is the reference dropped?

> +	if (np_conn) {
> +		np_edev = of_get_parent(np_conn);

Same question

> +
> +		chg->cable.edev = extcon_find_edev_by_node(np_edev);

You probably need device_link_add() as well. I don't think above extcon
code cares about it.

> +		if (IS_ERR(chg->cable.edev)) {
> +			/*
> +			 * In case of deferred extcon probe, defer our probe as well
> +			 * until it appears.
> +			 */
> +			if (PTR_ERR(chg->cable.edev) == -EPROBE_DEFER)
> +				return PTR_ERR(chg->cable.edev);
> +			/*
> +			 * Otherwise, ignore errors (the charger can run without a
> +			 * connector provided).
> +			 */
> +			dev_warn(dev, "no extcon device found in device-tree (%ld)\n",
> +				 PTR_ERR(chg->cable.edev));
> +		}
> +	}


Best regards,
Krzysztof