[7/9] xhci: Clear the host side toggle manually when endpoint is soft reset

[7/9] xhci: Clear the host side toggle manually when endpoint is soft reset

[Mathias Nyman]

Some devices use a clear endpoint halt request as a soft reset, even if
the endpoint is not halted. This will clear the toggle and sequence on the
device side.

xHCI however refuses to reset a non-halted endpoint, so instead
we need to issue a configure endpoint command on xHCI to clear its host
side toggle and sequence, and get it in sync with the device side.

This is a respin of a old patch that was reverted as it had a stale
endpoint context dequeue value which caused regression.
commit 27082e2654dc ("xhci: Clear the host side toggle manually when
endpoint is 'soft reset'")

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-ring.c |   5 ++-
 drivers/usb/host/xhci.c      | 105 ++++++++++++++++++++++++++++++++++++-------
 drivers/usb/host/xhci.h      |   2 +
 3 files changed, 95 insertions(+), 17 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 86476c6..91a1a82 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1829,9 +1829,10 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 
 	xhci_queue_reset_ep(xhci, command, slot_id, ep_index, reset_type);
 
-	if (reset_type == EP_HARD_RESET)
+	if (reset_type == EP_HARD_RESET) {
+		ep->ep_state |= EP_HARD_CLEAR_TOGGLE;
 		xhci_cleanup_stalled_ring(xhci, ep_index, stream_id, td);
-
+	}
 	xhci_ring_cmd_db(xhci);
 }
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index f9d8a32..05b22b8 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1356,6 +1356,11 @@ static int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flag
 		ret = -EINVAL;
 		goto free_priv;
 	}
+	if (*ep_state & EP_SOFT_CLEAR_TOGGLE) {
+		xhci_warn(xhci, "Can't enqueue URB while manually clearing toggle\n");
+		ret = -EINVAL;
+		goto free_priv;
+	}
 
 	switch (usb_endpoint_type(&urb->ep->desc)) {
 
@@ -2869,33 +2874,103 @@ void xhci_cleanup_stalled_ring(struct xhci_hcd *xhci, unsigned int ep_index,
 	}
 }
 
-/* Called when clearing halted device. The core should have sent the control
- * message to clear the device halt condition. The host side of the halt should
- * already be cleared with a reset endpoint command issued when the STALL tx
- * event was received.
+/*
+ * Called after usb core issues a clear halt control message.
+ * The host side of the halt should already be cleared by a reset endpoint
+ * command issued when the STALL event was received.
  *
- * Context: in_interrupt
+ * The reset endpoint command may only be issued to endpoints in the halted
+ * state. For software that wishes to reset the data toggle or sequence number
+ * of an endpoint that isn't in the halted state this function will issue a
+ * configure endpoint command with the Drop and Add bits set for the target
+ * endpoint. Refer to the additional note in xhci spcification section 4.6.8.
  */
 
 static void xhci_endpoint_reset(struct usb_hcd *hcd,
-		struct usb_host_endpoint *ep)
+		struct usb_host_endpoint *host_ep)
 {
 	struct xhci_hcd *xhci;
+	struct usb_device *udev;
+	struct xhci_virt_device *vdev;
+	struct xhci_virt_ep *ep;
+	struct xhci_input_control_ctx *ctrl_ctx;
+	struct xhci_command *stop_cmd, *cfg_cmd;
+	unsigned int ep_index;
+	unsigned long flags;
+	u32 ep_flag;
 
 	xhci = hcd_to_xhci(hcd);
+	if (!host_ep->hcpriv)
+		return;
+	udev = (struct usb_device *) host_ep->hcpriv;
+	vdev = xhci->devs[udev->slot_id];
+	ep_index = xhci_get_endpoint_index(&host_ep->desc);
+	ep = &vdev->eps[ep_index];
+
+	/* Bail out if toggle is already being cleared by a endpoint reset */
+	if (ep->ep_state & EP_HARD_CLEAR_TOGGLE) {
+		ep->ep_state &= ~EP_HARD_CLEAR_TOGGLE;
+		return;
+	}
+	/* Only interrupt and bulk ep's use data toggle, USB2 spec 5.5.4-> */
+	if (usb_endpoint_xfer_control(&host_ep->desc) ||
+	    usb_endpoint_xfer_isoc(&host_ep->desc))
+		return;
+
+	ep_flag = xhci_get_endpoint_flag(&host_ep->desc);
+
+	if (ep_flag == SLOT_FLAG || ep_flag == EP0_FLAG)
+		return;
+
+	stop_cmd = xhci_alloc_command(xhci, true, GFP_NOWAIT);
+	if (!stop_cmd)
+		return;
+
+	cfg_cmd = xhci_alloc_command_with_ctx(xhci, true, GFP_NOWAIT);
+	if (!cfg_cmd)
+		goto cleanup;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+
+	/* block queuing new trbs and ringing ep doorbell */
+	ep->ep_state |= EP_SOFT_CLEAR_TOGGLE;
 
 	/*
-	 * We might need to implement the config ep cmd in xhci 4.8.1 note:
-	 * The Reset Endpoint Command may only be issued to endpoints in the
-	 * Halted state. If software wishes reset the Data Toggle or Sequence
-	 * Number of an endpoint that isn't in the Halted state, then software
-	 * may issue a Configure Endpoint Command with the Drop and Add bits set
-	 * for the target endpoint. that is in the Stopped state.
+	 * Make sure endpoint ring is empty before resetting the toggle/seq.
+	 * Driver is required to synchronously cancel all transfer request.
+	 * Stop the endpoint to force xHC to update the output context
 	 */
 
-	/* For now just print debug to follow the situation */
-	xhci_dbg(xhci, "Endpoint 0x%x ep reset callback called\n",
-		 ep->desc.bEndpointAddress);
+	if (!list_empty(&ep->ring->td_list)) {
+		dev_err(&udev->dev, "EP not empty, refuse reset\n");
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		goto cleanup;
+	}
+	xhci_queue_stop_endpoint(xhci, stop_cmd, udev->slot_id, ep_index, 0);
+	xhci_ring_cmd_db(xhci);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	wait_for_completion(stop_cmd->completion);
+
+	spin_lock_irqsave(&xhci->lock, flags);
+
+	/* config ep command clears toggle if add and drop ep flags are set */
+	ctrl_ctx = xhci_get_input_control_ctx(cfg_cmd->in_ctx);
+	xhci_setup_input_ctx_for_config_ep(xhci, cfg_cmd->in_ctx, vdev->out_ctx,
+					   ctrl_ctx, ep_flag, ep_flag);
+	xhci_endpoint_copy(xhci, cfg_cmd->in_ctx, vdev->out_ctx, ep_index);
+
+	xhci_queue_configure_endpoint(xhci, cfg_cmd, cfg_cmd->in_ctx->dma,
+				      udev->slot_id, false);
+	xhci_ring_cmd_db(xhci);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	wait_for_completion(cfg_cmd->completion);
+
+	ep->ep_state &= ~EP_SOFT_CLEAR_TOGGLE;
+	xhci_free_command(xhci, cfg_cmd);
+cleanup:
+	xhci_free_command(xhci, stop_cmd);
 }
 
 static int xhci_check_streams_endpoint(struct xhci_hcd *xhci,
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index e4d7d3d..9f236da 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -921,6 +921,8 @@ struct xhci_virt_ep {
 #define EP_HAS_STREAMS		(1 << 4)
 /* Transitioning the endpoint to not using streams, don't enqueue URBs */
 #define EP_GETTING_NO_STREAMS	(1 << 5)
+#define EP_HARD_CLEAR_TOGGLE	(1 << 6)
+#define EP_SOFT_CLEAR_TOGGLE	(1 << 7)
 	/* ----  Related to URB cancellation ---- */
 	struct list_head	cancelled_td_list;
 	/* Watchdog timer for stop endpoint command to cancel URBs */