On 30 March 2016 at 18:58, Jun Li <jun...@nxp.com> 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. -- Baolin.wang Best Regards -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
