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

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Message-ID: <20160506094103.GF32359@shlinux2.ap.freescale.net>
Date:	Fri, 6 May 2016 17:41:03 +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 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?

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
> 
> --
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-- 

Best Regards,
Peter Chen