On Thu, 8 Aug 2013, Christian Lamparter wrote:
> Anyway, I do have a question about something else too.
>
> in ath9k_htc's hif_usb:
>
> > struct usb_host_interface *alt = &hif_dev->interface->altsetting[0];
> > struct usb_endpoint_descriptor *endp;
> > ...
> > /* On downloading the firmware to the target, the USB descriptor of EP4
> > * is 'patched' to change the type of the endpoint to Bulk. This will
> > * bring down CPU usage during the scan period. */
> >
> > for (idx = 0; idx < alt->desc.bNumEndpoints; idx++) {
> > endp = &alt->endpoint[idx].desc;
> > if ((endp->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
> > USB_ENDPOINT_XFER_INT) {
> > endp->bmAttributes &= ~USB_ENDPOINT_XFERTYPE_MASK;
> > endp->bmAttributes |= USB_ENDPOINT_XFER_BULK;
> >// endp->bInterval = 0;
> > }
> > }
>
> Alan, can you please tell us, if it is really safe to
> override the bmAttributes this way? After all (according to
> the comment) the device has "morphed" (EP4 has changed).
This does not look like a good idea. Why does the driver do it?
> Or, is it necessary for the driver call "usb_reset_device"
> or (usb_reset_configuration) in this case?
After loading firmware, a reset generally is necessary. Some devices
will do it themselves; others require you to call usb_reset_device().
Alan Stern
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