From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783AbcEWKMW (ORCPT ); Mon, 23 May 2016 06:12:22 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:35214 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545AbcEWKMT (ORCPT ); Mon, 23 May 2016 06:12:19 -0400 Subject: Re: [PATCH v8 13/14] usb: gadget: udc: adapt to OTG core To: Peter Chen References: <57399839.90706@ti.com> <573AD198.6030307@ti.com> <573C6347.6080705@ti.com> <573C719F.5010107@ti.com> <573D6C1C.4090600@ti.com> <20160521022940.GA15088@shlinux2> <20160523032149.GA20438@shlinux2> CC: Jun Li , "peter.chen@freescale.com" , "balbi@kernel.org" , "tony@atomide.com" , "gregkh@linuxfoundation.org" , "dan.j.williams@intel.com" , "mathias.nyman@linux.intel.com" , "Joao.Pinto@synopsys.com" , "sergei.shtylyov@cogentembedded.com" , "jun.li@freescale.com" , "grygorii.strashko@ti.com" , "yoshihiro.shimoda.uh@renesas.com" , "robh@kernel.org" , "nsekhar@ti.com" , "b-liu@ti.com" , "linux-usb@vger.kernel.org" , "linux-omap@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" From: Roger Quadros Message-ID: <5742D764.2010507@ti.com> Date: Mon, 23 May 2016 13:11:48 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <20160523032149.GA20438@shlinux2> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/05/16 06:21, Peter Chen wrote: > On Sat, May 21, 2016 at 10:29:40AM +0800, Peter Chen wrote: >> On Thu, May 19, 2016 at 10:32:44AM +0300, Roger Quadros wrote: >>> On 18/05/16 17:46, Jun Li wrote: >>>> >>>> >>>>>>> >>>>>>> I didn't want to have complex Kconfig so decided to have otg as >>>>>>> built-in only. >>>>>>> What do you want me to change in existing code? and why? >>>>>> >>>>>> Remove those stuff which only for pass diff driver config Like every >>>>>> controller driver need a duplicated >>>>>> >>>>>> static struct otg_hcd_ops ci_hcd_ops = { >>>>>> ... >>>>>> } >>>>> >>>>> This is an exception only. Every controller driver doesn't need to >>>>> implement hcd_ops. It is implemented in the hcd core. >>>>> >>>>>> >>>>>> And here is another example, for gadget connect, otg driver can >>>>>> directly call to usb_udc_vbus_handler() in drd state machine, but you >>>>>> create another interface: >>>>>> >>>>>> .connect_control = usb_gadget_connect_control, >>>>>> >>>>>> If the symbol is defined in one driver which is 'm', another driver >>>>>> reference it should be 'm' as well, then there is no this kind of >>>>>> problem as my understanding. >>>>> >>>>> That is fine as long as all are 'm'. but how do you solve the case when >>>>> Gadget is built in and host is 'm'? OTG has to be built-in and you will >>>>> need an hcd to gadget interface. >>>> >>>> Hcd to gadget interface? Or you want to say otg to host interface? >>> >>> Sorry, I meant to say host to otg interface. >>> >>>> >>>> I think hcd and gadget are independent each other, now >>>> >>>> Hcd --> otg; and gadget --> otg, (hcd and gadget use otg's symbol) >>> >>> It is actually a circular dependency for both. >>> hcd <--> otg and gadget <--> otg >>> >>> hcd -> otg for usb_otg_register/unregister_hcd >>> otg -> hcd for usb_add/remove_hcd, usb_bus_start_enum, usb_control_msg, usb_hub_find_child >>> >>> gadget -> otg for usb_otg_register/unregister_gadget >>> otg -> gadget for usb_gadget_start/stop, usb_udc_vbus_handler >>> >>> Now consider what will happen if I get rid of the otg_hcd and otg_gadget interfaces. >>> 'y' means built-in, 'm' means module. >>> >>> 1) hcd 'y', gadget 'y' >>> otg has to be 'y' for proper build. >>> >>> 2) hcd 'm', gadget 'm' >>> otg has to be 'm' for proper build. >>> >>> 3) hcd 'y', gadget 'm' >>> Build will fail always. >>> If otg is 'y', otg build will fail due to dependency on gadget. >>> If otg is 'm', hcd build will fail due to dependency on otg. >>> >>> 4) hcd 'm', gadget 'y' >>> Build will fail always. >>> If otg is 'y', otg build will fail due to dependency on hcd. >>> If otg is 'm', gadget build will fails due to dependency on otg. >>> >>> So I solve this problem by adding the otg_hcd_ops and otg_gadget_ops >>> to remove otg->hcd and otg->gadget dependency. >>> >>> Now we can address 3) and 4) like so >>> >>> 3) hcd 'y', gadget 'm' >>> otg has to be 'y' for proper build. >>> >>> 4) hcd 'm', gadget 'y' >>> otg has to be 'y' for proper build. >>> >> >> How about this: >> Moving usb_otg_register/unregister_hcd to host driver to remove >> dependency hcd->otg. And moving usb_otg_get_data to common.c. >> >> Delete the wait queue at usb-otg.c, and if calling usb_otg_get_data >> returns NULL, the host/device driver's probe return -EPROBE_DEFER. >> When the otg driver is probed successfully, the host/device will be >> re-probed again, and usb_otg_register_hcd will be called again. >> >> And let OTG depends on HCD && GADGET, and delete otg_hcd_ops and >> otg_gadget_ops. Below build dependency issues can be fixed. >> What do you think? >> >>> 1) hcd 'y', gadget 'y' >>> otg has to be 'y' for proper build. >>> >>> 2) hcd 'm', gadget 'm' >>> otg has to be 'm' for proper build. >>> >>> 3) hcd 'y', gadget 'm' >>> Build will fail always. >>> If otg is 'y', otg build will fail due to dependency on gadget. >>> If otg is 'm', hcd build will fail due to dependency on otg. >>> >>> 4) hcd 'm', gadget 'y' >>> Build will fail always. >>> If otg is 'y', otg build will fail due to dependency on hcd. >>> If otg is 'm', gadget build will fails due to dependency on otg. >> -- >> > > After thinking more, my suggestion can't work. How about moving > CONFIG_USB_OTG out of CONFIG_USB, in that case, CONFIG_USB_OTG > can only be built in. > I tried this but it still doesn't resolve 3 and 4. I.e. it can't be automatically set to 'y' when either of hcd/gadget is 'y' and the other is 'm'. I think some kconfig trickery can be done to get what we want. cheers, -roger