On Tue, Apr 21, 2015 at 10:34:01AM +0300, Roger Quadros wrote: > On 21/04/15 09:04, Peter Chen wrote: > > > >> > >> On 20/04/15 06:05, Peter Chen wrote: > >>> On Tue, Apr 14, 2015 at 01:41:47PM +0300, Roger Quadros wrote: > >>>> This is an attempt to centralize OTG/Dual-role functionality in the kernel. > >>>> As of now I've got Dual-role functionality working pretty reliably on > >>>> dra7-evm. xhci side of things for OTG/DRD use are fixed in > >>>> http://thread.gmane.org/gmane.linux.kernel/1923161 > >>> > >>> Hi Roger, > >>> > >>> Currently, there are two main problems for DRD/OTG framework. > >>> > >>> - For multi-platform supports, we may define CONFIG_USB_OTG, but the > >>> gadget should not add its otg descriptor to its configuration > >>> descriptors if it does not support one of otg features (SRP/HNP/ADP). > >>> Macpaul Lin's patch set [1] is the right way to do it. > >> > >> Agreed. That check (whether OTG descriptor can be added and which version > >> of it) has to be done at runtime and it must be added only if hardware supports > >> OTG _and_ kernel OTG support is enabled. > >> > > > > Ok, let's put this patch set in mainline first, since your patch set may need some > > information from it. > > > >>> - We are lack of framework to handle OTG (DRD) switch, it is great you > >>> are designing it. The main problem for this framework is how to handle > >>> DRD/OTG FSM unify. My thought is we add two paths for them separate. > >>> For easy, I suggest if the platform supports one of otg features, then > >>> it goes to fully otg fsm, else it goes to simply otg fsm (like your > >>> drd fsm). If you agree with it too, you may not need to add another > >> "dr_mode" > >>> value. > >> > >> It would be nice that way but unfortunately it does't work in all cases. > >> e.g. What if the SoC itself supports all OTG features but the board is not > >> designed for OTG. Or the product designer simply is not interested in full OTG > >> support but just dual-role. So we need some flexibility for the device > >> tree/platform-data to specify that. This is where a new "dr_mode" == "dual- > >> role" is needed. > >> > > > > Since "dr_mode" has been widely used now, if we add a new property for it, we > > need to change all drivers. > > > > Your OTG/DRD framework needs to (partial) use otg fsm, and we will not teach old > > driver to use it since there are some driver related stuffs. > > fair enough. Let's not change dr_mode then and decide based on other parameters. > > > > > SRP/HNP/ADP support can be board level capabilities, and we may consider the > > otg device which does not support otg fsm (hardware finishes fsm). So I suggest > > we have below properties at dts: > > > > - otg-support /* fully otg support */ > > - otg-fsm-support /* fully otg fsm support */ > > what is the difference between otg-support and otg-fsm-support? Like I mentioned at above, the hardware finishes HNP/SRP which does not use otg fsm code (usb-otg-fsm.c), most of legacy otg platforms (musb?) use this way, for these platforms, only need to set otg-support = 1 For platforms which software finishes HNP/SRP using otg fsm code, need to set both flags. For platforms which only do role switch through id pin, do not need to set both. > > > - otg-ver /* eh & otg supplement version */ > > we can get otg version from the OTG controller. What exactly is the > otg-ver in dts for? Since most of otg stuffs are software's, eg, for otg descriptor, we will only use otg 2.0 descriptor when both CONFIG_USB_OTG20 and otg-ver = 20 are set. > > > - adp-support /* board adp support */ > > - srp-support /* board srp support */ > > - hnp-support /* board hnp support */ > > So if these options are not provided in DTS but the OTG core supports them then > we keep the respective feature disabled? Yes. > Won't this need dts change for existing boards? Does you know any dts based platform supports hnp/srp? For chipidea platform, currently, we depends on kernel configurations (CONFIG_USB_OTG_FSM), but it is incorrect way. > > Instead how about having disable flags instead. > - adp-disable /* board doesn't support adp */ > - srp-disable /* board doesn't support srp */ > - hnp-disable /* board doesn't support hnp */ > > Now, if the flags are not provided in dts we use the OTG core's flags. > How the OTG core's know if it supports these? > > > > Currently, if CONFIG_USB_OTG and CONFIG_USB_OTG_FSM are enabled, we will > > have otg fsm code (usb-otg-fsm.c). > > > > if (otg-support & otg-fsm-support) > > this device has fully otg support, and will follow full otg fsm transitions. > > else > > this device is drd, and will follow simple otg fsm transtions. > > > > cheers, > -roger > -- 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
