Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935160AbdCJKw0 (ORCPT ); Fri, 10 Mar 2017 05:52:26 -0500 Received: from mail-ot0-f174.google.com ([74.125.82.174]:33022 "EHLO mail-ot0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934497AbdCJKwU (ORCPT ); Fri, 10 Mar 2017 05:52:20 -0500 MIME-Version: 1.0 In-Reply-To: References: <87zih3m73h.fsf@notabene.neil.brown.name>

From: Baolin Wang Date: Fri, 10 Mar 2017 18:52:14 +0800 Message-ID: Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with the usb gadget power negotation To: Jun Li Cc: NeilBrown , Felipe Balbi , Greg KH , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse , "robh@kernel.org" , Marek Szyprowski , Ruslan Bilovol , Peter Chen , Alan Stern , "grygorii.strashko@ti.com" , Yoshihiro Shimoda , Lee Jones , Mark Brown , John Stultz , Charles Keepax , "patches@opensource.wolfsonmicro.com" , Linux PM list , USB , "device-mainlining@lists.linuxfoundation.org" , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v2AAqVoW001008 Content-Length: 6640 Lines: 151 On 10 March 2017 at 16:27, Jun Li wrote: > Hi > >> -----Original Message----- >> From: Baolin Wang [mailto:baolin.wang@linaro.org] >> Sent: Friday, March 10, 2017 3:15 PM >> To: Jun Li >> Cc: NeilBrown ; Felipe Balbi ; Greg KH >> ; Sebastian Reichel ; Dmitry >> Eremin-Solenikov ; David Woodhouse >> ; robh@kernel.org; Marek Szyprowski >> ; Ruslan Bilovol ; >> Peter Chen ; Alan Stern >> ; grygorii.strashko@ti.com; Yoshihiro Shimoda >> ; Lee Jones ; >> Mark Brown ; John Stultz ; >> Charles Keepax ; >> patches@opensource.wolfsonmicro.com; Linux PM list > pm@vger.kernel.org>; USB ; device- >> mainlining@lists.linuxfoundation.org; LKML >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with >> the usb gadget power negotation >> >> On 10 March 2017 at 14:30, Jun Li wrote: >> >> >> > >> >> >> > Will generic phy need add extcon as well? >> >> >> >> >> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which >> >> >> will be common code. >> >> >> >> >> > >> >> > I mean the common code need add 'struct extcon_dev' into both >> >> > 'struct phy' and 'struct usb_phy', right? as some/new usb phy use >> >> > that generic phy >> >> driver. >> >> >> >> Ah, you remind me. Seems we need also add one 'struct extcon_dev' >> >> into 'struct phy'. >> >> >> >> >> > >> >> >> >> > >> >> >> >> >> Secondly, I also agreed with Peter's comments: Not only USB >> >> >> >> >> PHY to register an extcon, but also for the drivers which >> >> >> >> >> can detect USB charger type, it may be USB controller >> >> >> >> >> driver, USB type-c driver, pmic driver, and these drivers >> >> >> >> >> may not have an extcon device since the internal part can finish >> the vbus detect. >> >> >> >> > >> >> >> >> > Whichever part can detect vbus, the driver for that part must >> >> >> >> > be able to find the extcon and trigger a notification. >> >> >> >> > Maybe one part can detect VBUS, another can measure the >> >> >> >> > resistance on ID and a third can work through the state >> >> >> >> > machine to determine if D+ and D- are shorted together. >> >> >> >> > Somehow these three need to work together to determine what >> >> >> >> > is >> >> >> >> plugged >> >> >> >> > in to the external connection port. Somewhere there much an >> >> 'extcon' >> >> >> >> > device which represents that port and which the three devices >> >> >> >> > can find and can interact with. >> >> >> >> > I think it makes sense for the usb_phy to be the connection point. >> >> >> >> > Each of the devices can get to the phy, and the phy can get >> >> >> >> > to the >> >> >> extcon. >> >> >> >> > It doesn't matter very much if the usb phy driver creates the >> >> >> >> > extcon, or if something else creates the extcon and the phy >> >> >> >> > driver performs a lookup to find it (e.g. based on devicetree info). >> >> >> >> > >> >> >> >> > The point is that there is obviously an external physical >> >> >> >> > connection, and so there should be an 'extcon' device that >> >> represents it. >> >> >> >> >> >> >> >> Peter & Jun, is it OK for you every phy has one extcon device >> >> >> >> to receive VBUS notification, especially for detecting the >> >> >> >> charger type by >> >> >> software? >> >> >> >> >> >> >> > >> >> >> > My understanding is phy/usb_phy as the connection point, will >> >> >> > send the notification to PMIC driver which actually control the >> >> >> > charge current, also this will be done in your common framework, >> right? >> >> >> >> >> >> Not in USB charger framework. If we are all agree every usb_phy >> >> >> can register one extcon device, can get correct charger type and >> >> >> send out correct vbus_draw information, then we don't need USB >> >> >> charger framework as Neil suggested. So this will be okay for your >> >> >> case (especially for detecting the charger type by software) ? >> >> > >> >> > In my case, charger detection is done by controller driver and I >> >> > need do charger type detection internally, and only pass the >> >> > current draw info via phy which will send out, this seems ok for >> >> > me, but I think it will be good if you or someone can show us an >> >> > example user based on the >> >> design Neil suggested. >> >> > Will you work out that common code if this USB charger framework is >> >> > not >> >> needed? >> >> >> >> I will add a 'struct extcon_dev*' in 'struct usb_phy' and struct >> >> phy“. Others are already ready if everyone has no complain about >> >> current design, except >> > >> > Only adding extcon_dev into usb_phy/phy and all others are ready? >> > My understanding you will also do: >> > - We need find a central place to send the notification(phy common part). >> >> That will include these implementation when adding extcon_dev. >> > > OK, thanks. > >> > - If the extcon_dev is directly added in usb_phy/phy, PMIC needs some >> API to findup it. >> >> PMIC can find extcon device by phandle. > > extcon_dev(not a reference pointer) is directly added in usb_phy/phy, not via devicetree, > how PMIC find it by phandle? >From my understanding, here we should add one pointer (extcon_dev *), since usb phy is not one external connect device. > >> >> > >> >> my one concern. (I am afraid if it is enough to send out vbus draw >> >> information from USB phy driver, for example you will miss super >> >> speed (900mA), which need get the speed information from gadget >> >> driver.) >> >> >> > >> > Can we handle this in USB(so has super speed information) and just >> > send out 900mA directly? >> >> From Neil's suggestion, we only have one place to send out current >> information from usb phy, so I have this concern and doubt if we still need >> the USB charger framework. > > So if put it in phy/usb_phy, this is a problem, that only one place should have > the infor of both speed and usb state, how about put it at usb_gadget, then, > e.g. send the notification in usb_gadget_vbus_connect()? That is same what USB charger did, from this point, we need USB charger to send out vbus draw information according to speed and usb state. But I should listen to other guys suggestion. Peter and Felipe, what do you think? -- Baolin.wang Best Regards