On 23/05/16 13:34, Jun Li wrote: > Hi > >> -----Original Message----- >> From: Roger Quadros [mailto:rogerq@xxxxxx] >> Sent: Monday, May 23, 2016 6:12 PM >> To: Peter Chen <hzpeterchen@xxxxxxxxx> >> Cc: Jun Li <jun.li@xxxxxxx>; peter.chen@xxxxxxxxxxxxx; balbi@xxxxxxxxxx; >> tony@xxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; dan.j.williams@xxxxxxxxx; >> mathias.nyman@xxxxxxxxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx; >> sergei.shtylyov@xxxxxxxxxxxxxxxxxx; jun.li@xxxxxxxxxxxxx; >> grygorii.strashko@xxxxxx; yoshihiro.shimoda.uh@xxxxxxxxxxx; >> robh@xxxxxxxxxx; nsekhar@xxxxxx; b-liu@xxxxxx; linux-usb@xxxxxxxxxxxxxxx; >> linux-omap@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; >> devicetree@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH v8 13/14] usb: gadget: udc: adapt to OTG core >> >> 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'. > > USB_OTG only can be selected by *user*, can't be automatically set to > 'y' like you said, no matter what's hcd/gadget config, USB_OTG can be > disabled in any cases. Yes. I am on the same page with that. > > I think Peter's intention is to make USB_OTG to be 'bool', either disabled; > or built-in(if enabled), something like your original idea? I'm fine with my original idea if you guys can confirm :). cheers, -roger > > Li Jun > >> >> I think some kconfig trickery can be done to get what we want. >> >> cheers, >> -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
