On Mon, Feb 06, 2012 at 03:14:10PM -0500, Alan Stern wrote:
> > What is wrong processing one setup packet after the other?
>
> Suppose the host sends a Set-Interface request, and you delay handling
> it. If the delay is too long, the host will time out and cancel the
> request. Then the host sends some completely different request, such
> as Set-Feature. If your delayed response goes back now, the host will
> think you accepted the Set-Feature request and not realize that you
> really carried out the Set-Interface. In addition, the response to the
> Set-Feature request will remain sitting in the ep0 FIFO and never get
> sent, because the host won't ask for it.
The prepare status stage for Set-Interface at usb_composite_setup_continue
should not be sent to udc at this situation, we should cancel it if we
receive another setup packet.
Maybe We can add judgement at composite_setup and composite_delayed_setup.
At composite_setup
If (cdev->delay_status > 0 && !(ctrl->bRequest == USB_REQ_SET_INTERFACE |
ctrl->bRequest == USB_REQ_SET_CONFIGURATION)) {
/* last one is delayed_one, but current one is non delayed_one.
* We should cancel work item for set_interface and set_configuration
* handle.
*/
cdev->delay_status = 0;
}
At work item composite_delayed_setup
if (cdev->delay_status == 0)
return; /* do noop */
else (cdev->delay_status == 2) {
cdev->delay_status--;
return; /* Cancel current delayed setup handle,
* will handle the next setup handle.
*/
}
>
> Alan Stern
>
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--
Best Regards,
Peter Chen
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