>> When a control transfer has a short data stage, the xHCI controller >> generates >> two transfer events: a COMP_SHORT_TX event that specifies the >> untransferred >> amount, and a COMP_SUCCESS event. But when the data stage is not short, >> only the >> COMP_SUCCESS event occurs. Therefore, xhci-hcd must set urb->actual_length >> to >> urb->transfer_buffer_length while processing the COMP_SUCCESS event, >> unless >> urb->actual_length was set already by a previous COMP_SHORT_TX event. > > >> The driver checks this by seeing whether urb->actual_length == 0, but this >> alone >> is the wrong test, as it is entirely possible for a short transfer to have >> an >> urb->actual_length = 0. > > >> This patch changes the xhci driver to rely not only on the >> urb->actual_length, >> but also on the ep_ring->last_td_was_short flag, which is set to true when >> a >> COMP_SHORT_TX event is received. > > >> This fixes a bug which affected the HSO plugin, which relies on URBs with >> urb->actual_length == 0 to halt re-submitting the RX URB in the control >> endpoint. > > >> Signed-off-by: Aleksander Morgado <aleksander@xxxxxxxxxxxxx> >> --- >> drivers/usb/host/xhci-ring.c | 14 +++++++++----- >> 1 file changed, 9 insertions(+), 5 deletions(-) > > >> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c >> index 88da8d6..6b050f1 100644 >> --- a/drivers/usb/host/xhci-ring.c >> +++ b/drivers/usb/host/xhci-ring.c > > [...] >> >> @@ -2484,6 +2480,14 @@ static int handle_tx_event(struct xhci_hcd *xhci, >> ret = process_bulk_intr_td(xhci, td, event_trb, >> event, >> ep, &status); >> >> + /* Flag whether the just processed TRB was short. Do it >> after >> + * processing, so that the processor methods can also use >> this >> + * flag. */ > > > The preferred multi-line comment style is this: > > /* > * bla > * bla > */ > > [...] > > WBR, Sergei > Will submit then a v3 with that change. Cheers, -- Aleksander https://aleksander.es -- 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
