On Mon, May 23, 2016 at 01:36:51PM +0300, Roger Quadros wrote: > 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 :). > Please do it. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
