linux-kernel - RE: [PATCH v8 0/4] Introduce usb charger framework to deal with the usb gadget power negotation

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Date:	Tue, 29 Mar 2016 00:32:12 +0000
From:	Peter Chen <peter.chen@....com>
To:	Baolin Wang <baolin.wang@...aro.org>,
	Peter Chen <hzpeterchen@...il.com>
CC:	Felipe Balbi <balbi@...nel.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Peter Chen <peter.chen@...escale.com>,
	Alan Stern <stern@...land.harvard.edu>,
	"r.baldyga@...sung.com" <r.baldyga@...sung.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" 
	<patches@...nsource.wolfsonmicro.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	USB <linux-usb@...r.kernel.org>,
	"device-mainlining@...ts.linuxfoundation.org" 
	<device-mainlining@...ts.linuxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v8 0/4] Introduce usb charger framework to deal with the
 usb gadget power negotation

 
> 
> On 28 March 2016 at 15:13, Peter Chen <hzpeterchen@...il.com> wrote:
> > On Mon, Mar 28, 2016 at 02:51:40PM +0800, Baolin Wang wrote:
> >> On 25 March 2016 at 15:09, Peter Chen <hzpeterchen@...il.com> wrote:
> >> > On Thu, Mar 24, 2016 at 08:35:53PM +0800, Baolin Wang wrote:
> >> >> Currently the Linux kernel does not provide any standard
> >> >> integration of this feature that integrates the USB subsystem with
> >> >> the system power regulation provided by PMICs meaning that either
> >> >> vendors must add this in their kernels or USB gadget devices based
> >> >> on Linux (such as mobile phones) may not behave as they should. Thus
> provide a standard framework for doing this in kernel.
> >> >>
> >> >> Now introduce one user with wm831x_power to support and test the
> >> >> usb charger, which is pending testing. Moreover there may be other
> >> >> potential users will use it in future.
> >> >>
> >> >
> >> > I am afraid I still not find the user (udc driver) for this
> >> > framework, I would like to see how udc driver block the enumeration
> >> > until the charger detection has finished, or am I missing something?
> >>
> >> It is not for udc driver but for power users who want to negotiate
> >> with USB subsystem.
> >>
> >
> > Then, where is the code the test user to decide what kinds of USB
> > charger (SDP, CDP, DCP) is connecting now?
> 
> Users can choose to implement multiple ways to get the charger type In
> 'usb_charger_detect_type()' function.
> 
> >
 
Then, how you test your code? When we introduce an API, at least, there is one
user for it.

Peter