Messages in this thread | | | Date | Mon, 1 Jul 2013 16:41:17 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH] usb: Clear both buffers when clearing a control transfer TT buffer. |
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On Thu, 27 Jun 2013, William Gulland wrote:
> Control transfers have both IN and OUT (or SETUP) packets, so when > clearing TT buffers for a control transfer it's necessary to send > two HUB_CLEAR_TT_BUFFER requests to the hub. > > Signed-off-by: William Gulland <wgulland@google.com> > --- > drivers/usb/core/hub.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index feef935..868ad74 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -668,6 +668,15 @@ resubmit: > static inline int > hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt) > { > + /* Need to clear both directions for control ep */ > + if (((devinfo >> 11) & USB_ENDPOINT_XFERTYPE_MASK) == > + USB_ENDPOINT_XFER_CONTROL) { > + int status = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0), > + HUB_CLEAR_TT_BUFFER, USB_RT_PORT, > + devinfo ^ 0x8000, tt, NULL, 0, 1000); > + if (status) > + return status; > + } > return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0), > HUB_CLEAR_TT_BUFFER, USB_RT_PORT, devinfo, > tt, NULL, 0, 1000);
Well, this won't hurt much. And since it does seem to fix a hardware problem,
Acked-by: Alan Stern <stern@rowland.harvard.edu>
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