linux-kernel - Re: [PATCH v7 03/14] usb: hcd.h: Add OTG to HCD interface

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Message-ID: <20160510031401.GA3748@shlinux2.ap.freescale.net>
Date:	Tue, 10 May 2016 11:14:01 +0800
From:	Peter Chen <hzpeterchen@...il.com>
To:	Roger Quadros <rogerq@...com>
Cc:	peter.chen@...escale.com, stern@...land.harvard.edu,
	balbi@...nel.org, gregkh@...uxfoundation.org,
	dan.j.williams@...el.com, jun.li@...escale.com,
	mathias.nyman@...ux.intel.com, tony@...mide.com,
	Joao.Pinto@...opsys.com, abrestic@...omium.org,
	yoshihiro.shimoda.uh@...esas.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v7 03/14] usb: hcd.h: Add OTG to HCD interface

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@...com>
> >> Acked-by: Peter Chen <peter.chen@....com>
> > 
> > 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.

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@...r.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 

-- 

Best Regards,
Peter Chen