linux-kernel - RE: [PATCH v9 1/4] gadget: Introduce the usb charger framework

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Date:	Wed, 6 Apr 2016 08:26:45 +0000
From:	Jun Li <jun.li@....com>
To:	Baolin Wang <baolin.wang@...aro.org>,
	"balbi@...nel.org" <balbi@...nel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"sre@...nel.org" <sre@...nel.org>,
	"dbaryshkov@...il.com" <dbaryshkov@...il.com>,
	"dwmw2@...radead.org" <dwmw2@...radead.org>
CC:	"peter.chen@...escale.com" <peter.chen@...escale.com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"r.baldyga@...sung.com" <r.baldyga@...sung.com>,
	"yoshihiro.shimoda.uh@...esas.com" <yoshihiro.shimoda.uh@...esas.com>,
	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"broonie@...nel.org" <broonie@...nel.org>,
	"ckeepax@...nsource.wolfsonmicro.com" 
	<ckeepax@...nsource.wolfsonmicro.com>,
	"patches@...nsource.wolfsonmicro.com" 
	<patches@...nsource.wolfsonmicro.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"device-mainlining@...ts.linuxfoundation.org" 
	<device-mainlining@...ts.linuxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v9 1/4] gadget: Introduce the usb charger framework

Hi

> -----Original Message-----
> From: linux-usb-owner@...r.kernel.org [mailto:linux-usb-
> owner@...r.kernel.org] On Behalf Of Baolin Wang
> Sent: Friday, April 01, 2016 3:22 PM
> To: balbi@...nel.org; gregkh@...uxfoundation.org; sre@...nel.org;
> dbaryshkov@...il.com; dwmw2@...radead.org
> Cc: peter.chen@...escale.com; stern@...land.harvard.edu;
> r.baldyga@...sung.com; yoshihiro.shimoda.uh@...esas.com;
> lee.jones@...aro.org; broonie@...nel.org;
> ckeepax@...nsource.wolfsonmicro.com; patches@...nsource.wolfsonmicro.com;
> baolin.wang@...aro.org; linux-pm@...r.kernel.org; linux-
> usb@...r.kernel.org; device-mainlining@...ts.linuxfoundation.org; linux-
> kernel@...r.kernel.org
> Subject: [PATCH v9 1/4] gadget: Introduce the usb charger framework
> 

...

> +/*
> + * usb_charger_get_type() - get the usb charger type with lock protection.
> + * @uchger - usb charger device
> + *
> + * Users can get the charger type by this safe API, rather than using
> +the
> + * usb_charger structure directly.
> + */
> +enum usb_charger_type usb_charger_get_type(struct usb_charger *uchger)
> +{
> +	enum usb_charger_type type;
> +
> +	mutex_lock(&uchger->lock);
> +	type = uchger->type;
> +	mutex_unlock(&uchger->lock);
> +
> +	return type;
> +}
> +EXPORT_SYMBOL_GPL(usb_charger_get_type);
> +
> +/*
> + * usb_charger_detect_type() - detect the charger type manually.
> + * @uchger - usb charger device
> + *
> + * Note: You should ensure you need to detect the charger type manually
> +on your
> + * platform.
> + * You should call it at the right gadget state to avoid affecting
> +gadget
> + * enumeration.
> + */
> +int usb_charger_detect_type(struct usb_charger *uchger) {
> +	enum usb_charger_type type;
> +
> +	if (WARN(!uchger->charger_detect,
> +		 "charger detection method should not be NULL"))
> +		return -EINVAL;
> +
> +	type = uchger->charger_detect(uchger);
> +
> +	mutex_lock(&uchger->lock);
> +	uchger->type = type;
> +	mutex_unlock(&uchger->lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_charger_detect_type);
> +
> +/*
> + * usb_charger_get_type_by_others() - Get the usb charger type by the
> +callback
> + * which is implemented by users.
> + * @uchger - the usb charger device.
> + *
> + * Note: This function is just used for getting the charger type, not
> +for
> + * detecting charger type which might affect the DP/DM line when gadget
> +is on
> + * enumeration state.
> + */
> +static enum usb_charger_type
> +usb_charger_get_type_by_others(struct usb_charger *uchger) {
> +	if (uchger->type != UNKNOWN_TYPE)
> +		return uchger->type;
> +
> +	if (uchger->psy) {
> +		union power_supply_propval val;
> +
> +		power_supply_get_property(uchger->psy,
> +					  POWER_SUPPLY_PROP_CHARGE_TYPE,
> +					  &val);
> +		switch (val.intval) {
> +		case POWER_SUPPLY_TYPE_USB:
> +			uchger->type = SDP_TYPE;
> +			break;
> +		case POWER_SUPPLY_TYPE_USB_DCP:
> +			uchger->type = DCP_TYPE;
> +			break;
> +		case POWER_SUPPLY_TYPE_USB_CDP:
> +			uchger->type = CDP_TYPE;
> +			break;
> +		case POWER_SUPPLY_TYPE_USB_ACA:
> +			uchger->type = ACA_TYPE;
> +			break;
> +		default:
> +			uchger->type = UNKNOWN_TYPE;
> +			break;
> +		}
> +	} else if (uchger->get_charger_type) {
> +		uchger->type = uchger->get_charger_type(uchger);
> +	} else {
> +		uchger->type = UNKNOWN_TYPE;
> +	}
> +
> +	return uchger->type;
> +}
> +

I think we may don't need this usb_charger_get_type_by_others().
"uchger->type" is set in one place is enough, that is: by
uchger->charger_detect() in usb_charger_detect_type(), then
usb_charger_get_type_by_others() is replaced by usb_charger_get_type().

uchger->charger_detect() can have diff implementations no matter
what kind of mechanism is used, for your PMIC case, you can just
directly get the type value by power_supply_get_property();
with that, we can have one central place to set uchger->type.
After uchger->type is set, charger type detection is no need to be
involved until charger type changes.

Then next question is where is to call usb_charger_detect_type(),
We need make sure it finished before usb gadget connect.

Ideal is with your framework, diff users only need implement
uchger->charger_detect(). :)

Li Jun

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