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. 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? 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
