Patch "usb: xhci: fix checking ep busy for CFC" has been added to the 4.3-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    usb: xhci: fix checking ep busy for CFC

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-xhci-fix-checking-ep-busy-for-cfc.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 42df7215facf27be8d53e657dd4a12d4ebad0a44 Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Wed, 18 Nov 2015 10:48:21 +0200
Subject: usb: xhci: fix checking ep busy for CFC

From: Lu Baolu <baolu.lu@linux.intel.com>

commit 42df7215facf27be8d53e657dd4a12d4ebad0a44 upstream.

Function ep_ring_is_processing() checks the dequeue pointer
in endpoint context to know whether an endpoint is busy with
processing TRBs. This is not correct since dequeue pointer
field in an endpoint context is only valid when the endpoint
is in Halted or Stopped states. This buggy code causes audio
noise when playing sound with USB headset connected to host
controllers which support CFC (one of xhci 1.1 features).

This patch should exist in stable kernel since v4.3.

Reported-and-tested-by: YD Tseng <yd_tseng@asmedia.com.tw>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/host/xhci-ring.c |   32 ++++++--------------------------
 1 file changed, 6 insertions(+), 26 deletions(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3914,28 +3914,6 @@ cleanup:
 	return ret;
 }
 
-static int ep_ring_is_processing(struct xhci_hcd *xhci,
-		int slot_id, unsigned int ep_index)
-{
-	struct xhci_virt_device *xdev;
-	struct xhci_ring *ep_ring;
-	struct xhci_ep_ctx *ep_ctx;
-	struct xhci_virt_ep *xep;
-	dma_addr_t hw_deq;
-
-	xdev = xhci->devs[slot_id];
-	xep = &xhci->devs[slot_id]->eps[ep_index];
-	ep_ring = xep->ring;
-	ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);
-
-	if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) != EP_STATE_RUNNING)
-		return 0;
-
-	hw_deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
-	return (hw_deq !=
-		xhci_trb_virt_to_dma(ep_ring->enq_seg, ep_ring->enqueue));
-}
-
 /*
  * Check transfer ring to guarantee there is enough room for the urb.
  * Update ISO URB start_frame and interval.
@@ -4001,10 +3979,12 @@ int xhci_queue_isoc_tx_prepare(struct xh
 	}
 
 	/* Calculate the start frame and put it in urb->start_frame. */
-	if (HCC_CFC(xhci->hcc_params) &&
-			ep_ring_is_processing(xhci, slot_id, ep_index)) {
-		urb->start_frame = xep->next_frame_id;
-		goto skip_start_over;
+	if (HCC_CFC(xhci->hcc_params) && !list_empty(&ep_ring->td_list)) {
+		if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) ==
+				EP_STATE_RUNNING) {
+			urb->start_frame = xep->next_frame_id;
+			goto skip_start_over;
+		}
 	}
 
 	start_frame = readl(&xhci->run_regs->microframe_index);


Patches currently in stable-queue which might be from baolu.lu@linux.intel.com are

queue-4.3/usb-xhci-fix-checking-ep-busy-for-cfc.patch