Please tell your email client to fold lines after 72 columns or so. On Wed, 1 Nov 2017, Gervais, Francois wrote: > We are running the musb driver on a AM335 cpu paired with a microchip hub (USB2412). > > In one of our use-cases, we have a high chance of having an error on a bulk split transaction. Since the musb driver does not implement the clear TT buffer it leaves us with a TT buffer full on the hub which in turns NAK any new split transactions. > > To fix this problem, we added the Clear_TT_Buffer handling in case of a split transaction error, trying to match the spec as closely as possible. > > We came up with the following: > > diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c > index 26bda88..ac1a959 100755 > --- a/drivers/usb/musb/musb_host.c > +++ b/drivers/usb/musb/musb_host.c > @@ -376,6 +376,11 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb, > break; > } > > + if ((status || urb->unlinked) && > + (usb_pipecontrol(urb->pipe) || usb_pipebulk(urb->pipe)) && > + urb->dev->tt) > + usb_hub_clear_tt_buffer(urb); > + > qh->is_ready = 0; > musb_giveback(musb, urb, status); > qh->is_ready = ready; > > This seems to work in our case but we'd like to get feedback in order to improve the patch if needed. The patch is incomplete. You need to register a completion routine, as the .clear_tt_buffer_complete member of musb_hc_driver. This routine will be called after the Clear-TT-Buffer request has completed. Until that happens, you must not try to use the TT. For an example, see ehci_clear_tt_buffer_complete() in drivers/usb/host/ehci-q.c. Alan Stern -- 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
