The xhci driver was causing intermittent 5 second delays from the USB
keyboard polling hook.  Executing something like a "sleep 1" for
example would sleep for 5 seconds, unless an event occurred on
the USB bus to shorten the delay.

Modeled after the code in the DWC2 driver, a nonblock state was added
to quickly return instead of blocking for up to 5 seconds waiting for
an event before timing out.

Signed-off-by: Jason Wessel <jason.wes...@windriver.com>
---
 drivers/usb/host/xhci-ring.c | 26 +++++++++++++++++---------
 drivers/usb/host/xhci.c      | 11 ++++++-----
 include/usb/xhci.h           |  5 +++--
 3 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 86aeaab412..b7b2e16410 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -432,9 +432,11 @@ static int event_ready(struct xhci_ctrl *ctrl)
  *
  * @param ctrl         Host controller data structure
  * @param expected     TRB type expected from Event TRB
+ * @param nonblock     when true do not block waiting for response
  * @return pointer to event trb
  */
-union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected)
+union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected,
+                                   bool nonblock)
 {
        trb_type type;
        unsigned long ts = get_timer(0);
@@ -442,8 +444,11 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl 
*ctrl, trb_type expected)
        do {
                union xhci_trb *event = ctrl->event_ring->dequeue;
 
-               if (!event_ready(ctrl))
+               if (!event_ready(ctrl)) {
+                       if (nonblock)
+                               return NULL;
                        continue;
+               }
 
                type = TRB_FIELD_TO_TYPE(le32_to_cpu(event->event_cmd.flags));
                if (type == expected)
@@ -493,7 +498,7 @@ static void abort_td(struct usb_device *udev, int ep_index)
 
        xhci_queue_command(ctrl, NULL, udev->slot_id, ep_index, TRB_STOP_RING);
 
-       event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+       event = xhci_wait_for_event(ctrl, TRB_TRANSFER, false);
        field = le32_to_cpu(event->trans_event.flags);
        BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
        BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
@@ -501,7 +506,7 @@ static void abort_td(struct usb_device *udev, int ep_index)
                != COMP_STOP)));
        xhci_acknowledge_event(ctrl);
 
-       event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+       event = xhci_wait_for_event(ctrl, TRB_COMPLETION, false);
        BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
                != udev->slot_id || GET_COMP_CODE(le32_to_cpu(
                event->event_cmd.status)) != COMP_SUCCESS);
@@ -509,7 +514,7 @@ static void abort_td(struct usb_device *udev, int ep_index)
 
        xhci_queue_command(ctrl, (void *)((uintptr_t)ring->enqueue |
                ring->cycle_state), udev->slot_id, ep_index, TRB_SET_DEQ);
-       event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+       event = xhci_wait_for_event(ctrl, TRB_COMPLETION, false);
        BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
                != udev->slot_id || GET_COMP_CODE(le32_to_cpu(
                event->event_cmd.status)) != COMP_SUCCESS);
@@ -552,10 +557,11 @@ static void record_transfer_result(struct usb_device 
*udev,
  * @param pipe         contains the DIR_IN or OUT , devnum
  * @param length       length of the buffer
  * @param buffer       buffer to be read/written based on the request
+ * @param nonblock     when true do not block waiting for response
  * @return returns 0 if successful else -1 on failure
  */
 int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
-                       int length, void *buffer)
+                       int length, void *buffer, bool nonblock)
 {
        int num_trbs = 0;
        struct xhci_generic_trb *start_trb;
@@ -714,8 +720,10 @@ int xhci_bulk_tx(struct usb_device *udev, unsigned long 
pipe,
 
        giveback_first_trb(udev, ep_index, start_cycle, start_trb);
 
-       event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+       event = xhci_wait_for_event(ctrl, TRB_TRANSFER, nonblock);
        if (!event) {
+               if (nonblock)
+                       return -EINVAL;
                debug("XHCI bulk transfer timed out, aborting...\n");
                abort_td(udev, ep_index);
                udev->status = USB_ST_NAK_REC;  /* closest thing to a timeout */
@@ -911,7 +919,7 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long 
pipe,
 
        giveback_first_trb(udev, ep_index, start_cycle, start_trb);
 
-       event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+       event = xhci_wait_for_event(ctrl, TRB_TRANSFER, false);
        if (!event)
                goto abort;
        field = le32_to_cpu(event->trans_event.flags);
@@ -929,7 +937,7 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long 
pipe,
        if (GET_COMP_CODE(le32_to_cpu(event->trans_event.transfer_len))
                        == COMP_SHORT_TX) {
                /* Short data stage, clear up additional status stage event */
-               event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+               event = xhci_wait_for_event(ctrl, TRB_TRANSFER, false);
                if (!event)
                        goto abort;
                BUG_ON(TRB_TO_SLOT_ID(field) != slot_id);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index f635bb39f6..57d799e4cb 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -495,7 +495,7 @@ static int xhci_configure_endpoints(struct usb_device 
*udev, bool ctx_change)
        xhci_flush_cache((uintptr_t)in_ctx->bytes, in_ctx->size);
        xhci_queue_command(ctrl, in_ctx->bytes, udev->slot_id, 0,
                           ctx_change ? TRB_EVAL_CONTEXT : TRB_CONFIG_EP);
-       event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+       event = xhci_wait_for_event(ctrl, TRB_COMPLETION, false);
        BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
                != udev->slot_id);
 
@@ -691,7 +691,7 @@ static int xhci_address_device(struct usb_device *udev, int 
root_portnr)
        ctrl_ctx->drop_flags = 0;
 
        xhci_queue_command(ctrl, (void *)ctrl_ctx, slot_id, 0, TRB_ADDR_DEV);
-       event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+       event = xhci_wait_for_event(ctrl, TRB_COMPLETION, false);
        BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags)) != slot_id);
 
        switch (GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))) {
@@ -766,7 +766,7 @@ static int _xhci_alloc_device(struct usb_device *udev)
        }
 
        xhci_queue_command(ctrl, NULL, 0, 0, TRB_ENABLE_SLOT);
-       event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+       event = xhci_wait_for_event(ctrl, TRB_COMPLETION, false);
        BUG_ON(GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))
                != COMP_SUCCESS);
 
@@ -1152,6 +1152,7 @@ unknown:
  * @param buffer       buffer to be read/written based on the request
  * @param length       length of the buffer
  * @param interval     interval of the interrupt
+ * @param nonblock     when true do not block waiting for response
  * @return 0
  */
 static int _xhci_submit_int_msg(struct usb_device *udev, unsigned long pipe,
@@ -1169,7 +1170,7 @@ static int _xhci_submit_int_msg(struct usb_device *udev, 
unsigned long pipe,
         * (at most) one TD. A TD (comprised of sg list entries) can
         * take several service intervals to transmit.
         */
-       return xhci_bulk_tx(udev, pipe, length, buffer);
+       return xhci_bulk_tx(udev, pipe, length, buffer, nonblock);
 }
 
 /**
@@ -1189,7 +1190,7 @@ static int _xhci_submit_bulk_msg(struct usb_device *udev, 
unsigned long pipe,
                return -EINVAL;
        }
 
-       return xhci_bulk_tx(udev, pipe, length, buffer);
+       return xhci_bulk_tx(udev, pipe, length, buffer, false);
 }
 
 /**
diff --git a/include/usb/xhci.h b/include/usb/xhci.h
index 7d34103fd5..73db77fc02 100644
--- a/include/usb/xhci.h
+++ b/include/usb/xhci.h
@@ -1249,9 +1249,10 @@ void xhci_setup_addressable_virt_dev(struct xhci_ctrl 
*ctrl,
 void xhci_queue_command(struct xhci_ctrl *ctrl, u8 *ptr,
                        u32 slot_id, u32 ep_index, trb_type cmd);
 void xhci_acknowledge_event(struct xhci_ctrl *ctrl);
-union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected);
+union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected,
+                                   bool nonblock);
 int xhci_bulk_tx(struct usb_device *udev, unsigned long pipe,
-                int length, void *buffer);
+                int length, void *buffer, bool nonblock);
 int xhci_ctrl_tx(struct usb_device *udev, unsigned long pipe,
                 struct devrequest *req, int length, void *buffer);
 int xhci_check_maxpacket(struct usb_device *udev);
-- 
2.17.1

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