Hi > -----Original Message----- > From: Baolin Wang [mailto:baolin.wang@xxxxxxxxxx] > Sent: Thursday, March 31, 2016 1:23 PM > To: Jun Li <jun.li@xxxxxxx> > Cc: Peter Chen <hzpeterchen@xxxxxxxxx>; 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 v8 0/4] Introduce usb charger framework to deal with > the usb gadget power negotation > > On 30 March 2016 at 18:58, Jun Li <jun.li@xxxxxxx> wrote: > >> >> >> > Seems you don't want to guarantee charger type detection is > >> >> >> > done before gadget connection(pullup DP), right? > >> >> >> > I see you call usb_charger_detect_type() in each gadget usb > >> >> >> > state > >> >> >> changes. > >> >> >> > >> >> >> I am not sure I get your point correctly, please correct me if > >> >> >> I misunderstand you. > >> >> >> We need to check the charger type at every event comes from the > >> >> >> usb gadget state changes or the extcon device state changes, > >> >> >> which means a new charger plugin or pullup. > >> >> >> > >> >> > > >> >> > According to usb charger spec, my understanding is you can't do > >> >> > real charger detection procedure *after* gadget > >> >> > _connection_(pullup DP), also I don't > >> >> > >> >> Why can not? Charger detection is usually from PMIC. > >> > > >> > Charger detection process will impact DP/DM line state, see usb > >> > charger spec v1.2 for detail detection process, section 4.6.3 says: > >> > > >> > "A PD is allowed to *disconnect* and repeat the charger detection > >> > process multiple times while attached. The PD is required to wait > >> > for a time of at least TCP_VDM_EN max between disconnecting and > >> > restarting the charger detection process." > >> > > >> > As Peter mentioned, the charger detection should happen between > >> > VBUS detection and gadget pull up DP for first plug in case. So > >> > when&after gadget connect (pullup DP), you should already know the > charger type. > >> > >> Make sense. In our company's solution, charger detection can be done > >> by hardware from PMIC at first, then it will not affect the DP/DM > >> line when gadget starts to enumeration. > > > > I see, charger type detection is done automatically by PMIC when VBUS > > is detected in your case, you just assume the process is complete > > before SW do gadget connect. To make the framework common, you may do > one time charger type check when vbus is on, and save it to avoid repeat > charger type check. > > OK. I'll add one judgement to check if the charger type is set in > 'usb_charger_detect_type()' function. Just adding a judgement isn't enough here, your framework should make sure usb_charger_detect_type() is called before gadget connect, with that, the existing caller place just gets the charger type from the saved value. The real charger type detection done by usb_charger_detect_type() can be called only when vbus is on. e.g. maybe in usb_udc_vbus_handler() before usb_udc_connect_control(). > > -- > Baolin.wang > Best Regards ��.n��������+%������w��{.n�����{���)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
