On 08/22/2014 04:43 AM, Xuebing Wang wrote:
> static inline bool gadget_supports_altsettings(struct usb_gadget *gadget)
> {
> /* PXA 21x/25x/26x has no altsettings at all */
> if (gadget_is_pxa(gadget))
> return false;
>
> /* PXA 27x and 3xx have *broken* altsetting support */
> if (gadget_is_pxa27x(gadget))
> return false;
>
> /* Everything else is *presumably* fine ... */
> return true;
> }
Hmm. On hardware without altsetting support, isochronous endpoints
cannot be used. I wonder whether the gadget core should loudly complain
if it detects such a situation.
This is what the USB spec says in 5.6.3:
> All device default interface settings must not include any isochronous
> endpoints with non-zero data payload sizes (specified via
> wMaxPacketSize in the endpoint descriptor). Alternate interface
> settings may specify non-zero data payload sizes for isochronous
> endpoints.
Daniel
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