linux-kernel - Re: [PATCH v12 2/4] gadget: Support for the usb charger framework

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Date:	Wed, 29 Jun 2016 11:20:52 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	Baolin Wang <baolin.wang@...aro.org>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>, robh@...nel.org,
	Jun Li <jun.li@....com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Ruslan Bilovol <ruslan.bilovol@...il.com>,
	Peter Chen <peter.chen@...escale.com>,
	Alan Stern <stern@...land.harvard.edu>, r.baldyga@...sung.com,
	grygorii.strashko@...com,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Lee Jones <lee.jones@...aro.org>,
	Mark Brown <broonie@...nel.org>,
	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
	patches@...nsource.wolfsonmicro.com,
	Linux PM list <linux-pm@...r.kernel.org>,
	USB <linux-usb@...r.kernel.org>,
	device-mainlining@...ts.linuxfoundation.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12 2/4] gadget: Support for the usb charger framework


Hi,

Baolin Wang <baolin.wang@...aro.org> writes:
>> Baolin Wang <baolin.wang@...aro.org> writes:
>>> For supporting the usb charger, it adds the usb_charger_init() and
>>> usb_charger_exit() functions for usb charger initialization and exit.
>>>
>>> It will report to the usb charger when the gadget state is changed,
>>> then the usb charger can do the power things.
>>>
>>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>>> Reviewed-by: Li Jun <jun.li@....com>
>>> Tested-by: Li Jun <jun.li@....com>
>>
>> Before anything, I must say that I really liked this patch. It's
>> minimaly invasive to udc core and does all the necessary changes. If it
>> wasn't for the extra charger class, this would've been perfect.
>>
>> Can't you just tie a charger to a UDC and avoid the charger class
>> completely?
>>
>>>  static inline int usb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA)
>>>  {
>>> +     if (gadget->charger)
>>
>> I guess you could do this check inside
>> usb_gadget_set_cur_limit_by_type() itself.
>
> We will access the 'gadget->charger->type' member when issuing
> usb_gadget_set_cur_limit_by_type(), so I think I should leave the
> check here in next new version.

Here's what I mean:

int usb_charger_set_cur_limit(struct usb_gadget *gadget, unsigned int mA)
{
	struct usb_charger *charger;
        enum usb_charger_type type;

	if (!gadget->charger)
        	return 0;

        charger = gadget->charger;
        type = charger->type;

	return __usb_charger_set_cur_limit(charger, type, mA);
}

static inline int usb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA)
{
	usb_charger_set_cur_limit(gadget,  mA);

 	if (!gadget->ops->vbus_draw)
 		return -EOPNOTSUPP;
 	return gadget->ops->vbus_draw(gadget, mA);
}

-- 
balbi

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