Hi,
Manu Gautam <mgautam@xxxxxxxxxxxxxx> writes:
> The PIDs for Isochronous data transfers are incorrect
> for high bandwidth IN endpoints when the request length
> is less than EP wMaxPacketSize.
> As per spec correct PIDs for ISOC data transfers are:
> ->For request length < maxPayloadSize
> - DATA0,
> ->For maxPayloadSize < length < 2*maxPayloadSize
> - DATA0,DATA1
> ->For 2*maxPayloadSize < length < 3*maxPayloadSize
> - DATA2, DATA1, DATA0.
>
> Fix this by setting the PCM field of trb->size depending
> on request length rather than fixing it to the value
> depending on wMaxPacketSize.
>
> Ideally it shouldn't give any issues as dwc3 will send
> 0-length packet for next IN token if host sends even
> after receiving a short packet. Windows seems to ignore
> this but with MacOS frame loss observed when using f_uvc.
>
> Signed-off-by: Manu Gautam <mgautam@xxxxxxxxxxxxxx>
Roger, you guys have been using isoc transfers lately. Does this work
for you? Is the current setup really buggy in any way?
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index aea9a5b..b81547d 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -854,8 +854,13 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
> trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS_FIRST;
>
> if (speed == USB_SPEED_HIGH) {
> - struct usb_ep *ep = &dep->endpoint;
> - trb->size |= DWC3_TRB_SIZE_PCM1(ep->mult - 1);
> + unsigned int maxp = usb_endpoint_maxp(
> + dep->endpoint.desc);
> + unsigned int rem = length % maxp;
> + unsigned int mult = (length / maxp) & 0x3;
> +
> + trb->size |= DWC3_TRB_SIZE_PCM1(
> + rem ? mult : mult - 1);
Manu, It seems to me like we shouldn't be relying on req->length. Which
gadget driver are you using to test this?
cheers
--
balbi
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
