usb: xhci: Add Clear_TT_Buffer

USB 2.0 specification chapter 11.17.5 says "as part of endpoint halt
processing for full-/low-speed endpoints connected via a TT, the host
software must use the Clear_TT_Buffer request to the TT to ensure
that the buffer is not in the busy state".

In our case, a full-speed speaker (ConferenceCam) is behind a high-
speed hub (ConferenceCam Connect), sometimes once we get STALL on a
request we may continue to get STALL with the folllowing requests,
like Set_Interface.

Here we invoke usb_hub_clear_tt_buffer() to send Clear_TT_Buffer
request to the hub of the device for the following Set_Interface
requests to the device to get ACK successfully.

Signed-off-by: Jim Lin <jilin@nvidia.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index feffceb31e8a..a52fd96e70e9 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -399,7 +399,7 @@ void xhci_ring_ep_doorbell(struct xhci_hcd *xhci,
 	 * stream once the endpoint is on the HW schedule.
 	 */
 	if ((ep_state & EP_STOP_CMD_PENDING) || (ep_state & SET_DEQ_PENDING) ||
-	    (ep_state & EP_HALTED))
+	    (ep_state & EP_HALTED) || (ep_state & EP_CLEARING_TT))
 		return;
 	writel(DB_VALUE(ep_index, stream_id), db_addr);
 	/* The CPU has better things to do at this point than wait for a
@@ -433,6 +433,13 @@ static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
 	}
 }
 
+void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
+		unsigned int slot_id,
+		unsigned int ep_index)
+{
+	ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
+}
+
 /* Get the right ring for the given slot_id, ep_index and stream_id.
  * If the endpoint supports streams, boundary check the URB's stream ID.
  * If the endpoint doesn't support streams, return the singular endpoint ring.
@@ -1794,6 +1801,23 @@ struct xhci_segment *trb_in_td(struct xhci_hcd *xhci,
 	return NULL;
 }
 
+static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci, struct xhci_td *td,
+		struct xhci_virt_ep *ep)
+{
+	/*
+	 * As part of low/full-speed endpoint-halt processing
+	 * we must clear the TT buffer (USB 2.0 specification 11.17.5).
+	 */
+	if (td->urb->dev->tt && !usb_pipeint(td->urb->pipe) &&
+	    (td->urb->dev->tt->hub != xhci_to_hcd(xhci)->self.root_hub) &&
+	    !(ep->ep_state & EP_CLEARING_TT)) {
+		ep->ep_state |= EP_CLEARING_TT;
+		td->urb->ep->hcpriv = td->urb->dev;
+		if (usb_hub_clear_tt_buffer(td->urb))
+			ep->ep_state &= ~EP_CLEARING_TT;
+	}
+}
+
 static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 		unsigned int slot_id, unsigned int ep_index,
 		unsigned int stream_id, struct xhci_td *td,
@@ -1812,6 +1836,7 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 	if (reset_type == EP_HARD_RESET) {
 		ep->ep_state |= EP_HARD_CLEAR_TOGGLE;
 		xhci_cleanup_stalled_ring(xhci, ep_index, stream_id, td);
+		xhci_clear_hub_tt_buffer(xhci, td, ep);
 	}
 	xhci_ring_cmd_db(xhci);
 }