Messages in this thread | | | Date | Wed, 28 Oct 2015 15:27:10 +0200 | From | Mathias Nyman <> | Subject | Re: [PATCH 1/1] usb: xhci: fix checking ep busy for CFC |
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On 28.10.2015 03:36, Lu Baolu wrote: > 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> > --- > drivers/usb/host/xhci-ring.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c > index fa83625..2b50d45 100644 > --- a/drivers/usb/host/xhci-ring.c > +++ b/drivers/usb/host/xhci-ring.c > @@ -3903,7 +3903,6 @@ static int ep_ring_is_processing(struct xhci_hcd *xhci, > 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]; > @@ -3913,9 +3912,7 @@ static int ep_ring_is_processing(struct xhci_hcd *xhci, > 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)); > + return !list_empty(&ep_ring->td_list); > }
Would it make sense to remove the ep_ring_is_processing() function completely?
It is only called in one place, and the main use is checking list_empty(&ep_ring->td_list). This could be checked directly in xhci_queue_isoc_tx_prepare()
-Mathias
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