On Mon, 1 Jul 2013, Victor Yeo wrote:
> Yes, UDC driver has bug. After modifying it, it can receive Set-Config
> request with a config value of 0. However, the "device descriptor test
> - addressed state" still fails.
>
> Please see the attached log. The Set-Config request with a config
> value of 0 is the second last USB request sent from the host. The last
> USB request is Get-Config, which still returns config value of 1.
This looks like another bug in the UDC driver. It performs the Status
stage of the Set-Config request before the gadget driver has finished
carrying out the request.
Notice that the USB_REQ_SET_CONFIGURATION case in standard_setup_req()
returns DELAYED_STATUS. As a result, fsg_setup() does not call
ep0_queue(), and so usb_ep_queue() doesn't get called. The UDC driver
is not supposed to ACK the Status stage of an OUT control transfer
until usb_ep_queue() is called.
> In gadget driver, do_set_config(), if new_config is 0, the new_config
> is not processed. So config value of zero will never be saved by
> gadget driver. Isn't it?
Look at do_set_config():
/* Disable the single interface */
if (fsg->config != 0) {
DBG(fsg, "reset config\n");
fsg->config = 0;
rc = do_set_interface(fsg, -1);
}
/* Enable the interface */
if (new_config != 0) {
...
}
return rc;
So if new_config is 0, fsg->config remains set to 0 and the
deconfiguration is processed by the do_set_interface() call.
Alan Stern
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