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. > >> >> 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 >>>>> >>> -- 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
