From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752873AbcEWD0y (ORCPT ); Sun, 22 May 2016 23:26:54 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:34995 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752720AbcEWD0v (ORCPT ); Sun, 22 May 2016 23:26:51 -0400 Date: Mon, 23 May 2016 11:21:49 +0800 From: Peter Chen To: Roger Quadros 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" Subject: Re: [PATCH v8 13/14] usb: gadget: udc: adapt to OTG core Message-ID: <20160523032149.GA20438@shlinux2> References: <57399839.90706@ti.com> <573AD198.6030307@ti.com> <573C6347.6080705@ti.com> <573C719F.5010107@ti.com> <573D6C1C.4090600@ti.com> <20160521022940.GA15088@shlinux2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160521022940.GA15088@shlinux2> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Best Regards, Peter Chen