linux-kernel - Re: [PATCH v10 1/4] gadget: Introduce the usb charger framework

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Date:	Fri, 8 Apr 2016 19:00:25 +0800
From:	Baolin Wang <baolin.wang@...aro.org>
To:	Jun Li <jun.li@....com>
Cc:	"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>,
	"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 v10 1/4] gadget: Introduce the usb charger framework

Hi Jun,

>> >> +/*
>> >> + * 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);
>> >
>> > I still recommend have a central place to call
>> > usb_charger_detect_type() to cover real charger detection instead of
>> > leaving this question open to diff users. This can be done after
>> > vbus-on is detected and before do gadget connect. I don't think this
>> will make your framework complicated.
>>
>> This API is used for detecting the charger type manually (software charger
>> detection), so if user's udc driver is needed to do this, then they can
>> issue it at their right place to make it more flexible. But let us see
>> other people's suggestion. Thanks.
>
> Ok, actually this API can be used for what ever charger detection
> type, user can implement any method(manual detection, directly read
> result from some HW...what ever) in uchger->charger_detect(), target is

But reading result from some HW dose not means *detect*, actually is
*get*. We can not mix them together with the different semantics.

> to have the charger type and set uchger->type, then you no need to add the comments/description to limit it usage. Also I do see there is possible
> central place to do this.
>

-- 
Baolin.wang
Best Regards