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. > > 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. 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). A general question, 2 drivers depends on each other, allowable? > > cheers, > -roger > > > > > Peter > >> cheers, > >> -roger > >> > >>> > >>> Peter > >>> > >>>> --- > >>>> 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 > >>> > > -- 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
