Re: [PATCH 1/2] usb: gadget: composite: Allow function drivers todefer setup responses

[Roger Quadros]

On 04/19/2011 05:23 PM, ext Michal Nazarewicz wrote:
> On Tue, 19 Apr 2011 15:33:52 +0200, Roger Quadros <roger.quadros@xxxxxxxxx> wrote:
> > @@ -895,6 +904,14 @@ composite_setup(struct usb_gadget *gadget, const struct
> > usb_ctrlrequest *ctrl)
> > if (w_value && !f->set_alt)
> > break;
> > value = f->set_alt(f, w_index, w_value);
> > + if (value == USB_GADGET_DELAYED_STATUS) {
> > + DBG(cdev,
> > + "%s: interface %d (%s) requested delayed status\n",
> > + __func__, intf, f->name);
> > + cdev->delayed_status++;
>
> Do we need it to be a counter? Won't simple flag do?

Counter because multiple interfaces could return USB_GADGET_DELAYED_STATUS
and we need to know how many of them call usb_composite_setup_continue() before 
we actually complete the control transfer.

> > + DBG(cdev, "delayed_status count %d\n",
> > + cdev->delayed_status);
> > + }
> > break;
> > case USB_REQ_GET_INTERFACE:
> > if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE))
>
> > @@ -1289,3 +1310,41 @@ void usb_composite_unregister(struct
> > usb_composite_driver *driver)
> > return;
> > usb_gadget_unregister_driver(&composite_driver);
> > }
> > +
> > +/**
> > + * usb_composite_setup_continue() - Continue the delayed setup transfer
> > + * @cdev: the composite device who's setup transfer was delayed
> > + *
> > + * This function must be called by the USB function driver to continue
> > + * with the setup transfer's data/status phase in case it had requested to
> > + * delay the status phase. A USB function's setup handler (e.g. set_alt())
> > + * can request the composite framework to delay the setup request's status phase
> > + * by returning USB_GADGET_DELAYED_STATUS.
> > + */
> > +void usb_composite_setup_continue(struct usb_composite_dev *cdev)
> > +{
> > + int value;
> > + struct usb_request *req = cdev->req;
> > + unsigned long flags;
> > +
> > + DBG(cdev, "%s\n", __func__);
> > + spin_lock_irqsave(&cdev->lock, flags);
> > +
> > + if (cdev->delayed_status == 0) {
> > + WARN(cdev, "%s: Unexpected call\n", __func__);
> > +
> > + } else if (--cdev->delayed_status == 0) {
> > + DBG(cdev, "%s: Completing delayed status\n", __func__);
> > + req->length = 0;
> > + req->zero = 1;
> > + value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
> > + if (value < 0) {
> > + DBG(cdev, "ep_queue --> %d\n", value);
> > + req->status = 0;
> > + composite_setup_complete(cdev->gadget->ep0, req);
> > + }
> > + }Data/status stage.
> > +
> > + spin_unlock_irqrestore(&cdev->lock, flags);
> > +}
>
> It's just my opinion but I dislike how it looks almost identical to the end
> of composite_setup. I would rather make it more general (take value as
> argument for instance) and let composite_setup() call it.

Yes that could be done. I'll try to do so in the next iteration.

> > diff --git a/include/linux/usb/composite.h @@ -37,6 +37,15 @@
> > #include <linux/usb/ch9.h>
> > #include <linux/usb/gadget.h>
> > +/*
> > + * USB function drivers should return USB_GADGET_DELAYED_STATUS if they
> > + * wish to delay the status phase of the setup transfer till they are
> > + * ready. The composite framework will then delay the data/status phase
> > + * of the setup transfer till all the function drivers that requested for
> > + * USB_GADGET_DELAYED_STAUS, invoke usb_composite_setup_continue().
> > + *
> > + */
> > +#define USB_GADGET_DELAYED_STATUS 0x7fff /* Impossibly large value */
>
> I was wondering if we could change it to something like EDELAYED and put it to
> <include/linux/errno.h>. Just thinking, it may be a bad idea.

I would not do it.

Thanks for review.

--
regards,
-roger
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