Hi,
On Mon, Aug 29, 2011 at 02:35:29PM +0300, Felipe Balbi wrote:
> > >diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> > >index a6fc5c3..9d8ec02 100644
> > >--- a/drivers/usb/dwc3/ep0.c
> > >+++ b/drivers/usb/dwc3/ep0.c
> > >@@ -185,10 +185,27 @@ static int __dwc3_gadget_ep0_queue(struct dwc3_ep *dep,
> > > req->epnum = dep->number;
> > >
> > > list_add_tail(&req->list, &dep->request_list);
> > >- dwc3_map_buffer_to_dma(req);
> > >+ if (req->request.length == 0) {
> > >+ ret = dwc3_ep0_start_trans(dwc, dep->number,
> > >+ dwc->ctrl_req_addr, 0);
> > >+ } else if ((req->request.length % dep->endpoint.maxpacket)
> > >+ && (dep->number == 0)) {
> >
> > This "problem" is not limited to ep0. And I would beat the gadget
> > drivers to queue [bw]MaxPacketSize0? length requests even if they know
> > that they expect only 5 bytes of data. Otherwise this workaround as to
> > be implemented in other driver as well. It gets a little more
> > complicated if the requests is maxpacket+3 or so.
> >
> > So I'm for fixing the gadget.
>
> We could go that path, sure. But then this means that gadget driver will
> be doing something different than requested on specification, just
> because this one controller is quirky.
>
> A better approach might be to introduce a "quirks" field on struct
> usb_gadget, as have gadget drivers check for that. Something like:
>
> if (gadget->quirks & GADGET_NEEDS_ALIGNED_OUT)
> req->length = gadget->ep0->maxpacket;
> else
> req->length = len;
>
> but then, gadget driver needs to cope with whatever size we might need
> to send. In case of most gadget drivers, it's very simple because they
> will only receive data which is less than or equal to wMaxPacketSize,
> but on gadget drivers such as DFU, we might need to be careful here.
something else I forgot to mention:
If we're gonna have only one user for this, then I don't see the point
of changing the gadget framework or gadget driver(s). If we see more
controllers with similar limitations, then we might want to add a quirks
field to struct usb_gadget (or struct usb_udc).
--
balbi
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