RE: [PATCH v9 2/4] gadget: Support for the usb charger framework

[Felipe Balbi]

Hi,

Jun Li <jun.li@xxxxxxx> writes:
>> -----Original Message-----
>> From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-
>> owner@xxxxxxxxxxxxxxx] On Behalf Of Baolin Wang
>> Sent: Wednesday, April 06, 2016 6:47 PM
>> To: Peter Chen <hzpeterchen@xxxxxxxxx>
>> Cc: Felipe Balbi <balbi@xxxxxxxxxx>; Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>;
>> Sebastian Reichel <sre@xxxxxxxxxx>; Dmitry Eremin-Solenikov
>> <dbaryshkov@xxxxxxxxx>; David Woodhouse <dwmw2@xxxxxxxxxxxxx>; Peter Chen
>> <peter.chen@xxxxxxxxxxxxx>; Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>;
>> r.baldyga@xxxxxxxxxxx; Yoshihiro Shimoda
>> <yoshihiro.shimoda.uh@xxxxxxxxxxx>; Lee Jones <lee.jones@xxxxxxxxxx>; Mark
>> Brown <broonie@xxxxxxxxxx>; Charles Keepax
>> <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx>; patches@xxxxxxxxxxxxxxxxxxxxxxxxxxx;
>> Linux PM list <linux-pm@xxxxxxxxxxxxxxx>; USB <linux-usb@xxxxxxxxxxxxxxx>;
>> device-mainlining@xxxxxxxxxxxxxxxxxxxxxxxxx; LKML <linux-
>> kernel@xxxxxxxxxxxxxxx>
>> Subject: Re: [PATCH v9 2/4] gadget: Support for the usb charger framework
>> 
>> On 6 April 2016 at 15:19, Peter Chen <hzpeterchen@xxxxxxxxx> wrote:
>> > On Fri, Apr 01, 2016 at 03:21:50PM +0800, Baolin Wang wrote:
>> >>
>> >> @@ -563,6 +564,8 @@ struct usb_gadget_ops {
>> >>       struct usb_ep *(*match_ep)(struct usb_gadget *,
>> >>                       struct usb_endpoint_descriptor *,
>> >>                       struct usb_ss_ep_comp_descriptor *);
>> >> +     /* get the charger type */
>> >> +     enum usb_charger_type (*get_charger_type)(struct usb_gadget *);
>> >>  };
>> >
>> > Since we already have get_charger_type callback at usb_charger
>> > structure, why we still need this API at usb_gadget_ops?
>> 
>> In case some users want to get charger type at gadget level.
>> 
> Why gadget needs to know charger type? I also don't catch the intent of

because some gadgets need to call usb_gadget_vbus_draw(), although for
that they need power in mA rather.

> This api, as my understanding, gadget only need report gadget state changes.
> All information required for usb charger is charger type and gadget state.

you're making an assumption about how the HW is laid out which might not
be true.

-- 
balbi

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