On Tue, May 10, 2016 at 12:20:28PM +0300, Roger Quadros wrote: > On 10/05/16 11:03, Jun Li wrote: > > Hi > > > >> -----Original Message----- > >> From: Roger Quadros [mailto:rogerq@xxxxxx] > >> Sent: Tuesday, May 10, 2016 3:35 PM > >> To: Peter Chen <hzpeterchen@xxxxxxxxx> > >> Cc: peter.chen@xxxxxxxxxxxxx; stern@xxxxxxxxxxxxxxxxxxx; balbi@xxxxxxxxxx; > >> gregkh@xxxxxxxxxxxxxxxxxxx; dan.j.williams@xxxxxxxxx; jun.li@xxxxxxxxxxxxx; > >> mathias.nyman@xxxxxxxxxxxxxxx; tony@xxxxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx; > >> abrestic@xxxxxxxxxxxx; yoshihiro.shimoda.uh@xxxxxxxxxxx; linux- > >> usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux- > >> omap@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH v7 03/14] usb: hcd.h: Add OTG to HCD interface > >> > >> On 10/05/16 06:14, Peter Chen wrote: > >>> On Mon, May 09, 2016 at 12:45:38PM +0300, Roger Quadros wrote: > >>>> On 06/05/16 12:41, Peter Chen wrote: > >>>>> On Mon, May 02, 2016 at 03:18:46PM +0300, Roger Quadros wrote: > >>>>>> The OTG core will use struct otg_hcd_ops to interface with the HCD > >>>>>> controller. > >>>>>> > >>>>>> The main purpose of this interface is to avoid directly calling HCD > >>>>>> APIs from the OTG core as they wouldn't be defined in the built-in > >>>>>> symbol table if CONFIG_USB is m. > >>>>>> > >>>>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx> > >>>>>> Acked-by: Peter Chen <peter.chen@xxxxxxx> > >>>>> > >>>>> Roger, after thinking more, I still think current dependency between > >>>>> OTG, HCD and gadget are too complicated. Since the OTG can't work if > >>>>> it is built as module, I suggest letting OTG depends on HCD && > >>>>> USB_GADGET, and it is a boolean, in that case, we don't need to > >>>>> export any HCD and gadget ops, things will be much simpler. > >>>>> What's your opinion? > >>>> > >>>> How will it work if HCD and USB_GADGET are modules and OTG is built-in? > >>>> > >>> > >>> The OTG will not be compiled at this situation, since it is boolean. > >>> In fact, like I mentioned at above, OTG or USB function can't work if > >>> it is built as module. > >> > >> Isn't this a limitation? > >> As per the current implementation dual role works fine even with both > >> USB_GADGET and HCD as module. > > > > My understand: only make sense for pass build, host can't work before > > gadget modules loaded; gadget can't work before hcd loaded, nothing > > can work before all drivers are loaded. > > I can make OTG depend on GADGET and HCD, no issue with that. > But we can't get rid of the OTG to HCD/Gadged interfaces as we want things > to work with GADGET and HCD as modules. > Let's make OTG depends on gadget and hcd at Kconfig, and keep others unchanging, if no one objects it. Peter > > > >> > >> In the real world it is unlikely that GADGET and HCD will be built-in. > > > > Why? User enable USB_OTG means both drivers should be enabled anyway. > > Enabled, but not necessarily built-in. Most distributions don't have them > as built-in. > > But let's not argue in that direction. Let's say that they can be either > built-in or modules. > > > Even in non-OTG case, both may be built-in for machine with 2 ports > > (one port is host only, the other one is peripheral only). > > Sure. Every system designer is free to select the configuration. > > > > > A general question, 2 drivers depends on each other, allowable? > > I don't thing that's possible. Kconfig will complain. > http://lxr.free-electrons.com/source/Documentation/kbuild/kconfig-language.txt#L397 > > cheers, > -roger > > >>>>> > >>>>>> --- > >>>>>> include/linux/usb/hcd.h | 24 ++++++++++++++++++++++++ > >>>>>> 1 file changed, 24 insertions(+) > >>>>>> > >>>>>> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h > >>>>>> index b98f831..861ccaa 100644 > >>>>>> --- a/include/linux/usb/hcd.h > >>>>>> +++ b/include/linux/usb/hcd.h > >>>>>> @@ -399,6 +399,30 @@ struct hc_driver { > >>>>>> > >>>>>> }; > >>>>>> > >>>>>> +/** > >>>>>> + * struct otg_hcd_ops - Interface between OTG core and HCD > >>>>>> + * > >>>>>> + * Provided by the HCD core to allow the OTG core to interface > >>>>>> +with the HCD > >>>>>> + * > >>>>>> + * @add: function to add the HCD > >>>>>> + * @remove: function to remove the HCD > >>>>>> + * @usb_bus_start_enum: function to immediately start bus > >>>>>> +enumeration > >>>>>> + * @usb_control_msg: function to build and send of a control urb > >>>>>> + * @usb_hub_find_child: function to get pointer to the child > >>>>>> +device */ struct otg_hcd_ops { > >>>>>> + int (*add)(struct usb_hcd *hcd, > >>>>>> + unsigned int irqnum, unsigned long irqflags); > >>>>>> + void (*remove)(struct usb_hcd *hcd); > >>>>>> + int (*usb_bus_start_enum)(struct usb_bus *bus, unsigned int > >> port_num); > >>>>>> + int (*usb_control_msg)(struct usb_device *dev, unsigned int > >> pipe, > >>>>>> + __u8 request, __u8 requesttype, __u16 value, > >>>>>> + __u16 index, void *data, __u16 size, > >>>>>> + int timeout); > >>>>>> + struct usb_device * (*usb_hub_find_child)(struct usb_device > >> *hdev, > >>>>>> + int port1); > >>>>>> +}; > >>>>>> + > >>>>>> static inline int hcd_giveback_urb_in_bh(struct usb_hcd *hcd) { > >>>>>> return hcd->driver->flags & HCD_BH; > >>>>>> -- > >>>>>> 2.7.4 > >>>>>> > >>>>>> -- > >>>>>> 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 > >>>>> > >>> -- Best Regards, Peter Chen -- 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
