Re: [PATCH v2 1/1] usb: xhci: fix checking ep busy for CFC

[Lu, Baolu]

On 10/29/2015 08:51 PM, Sergei Shtylyov wrote:
> Hello.
>
> On 10/29/2015 5:46 AM, 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@xxxxxxxxxxxxxx>
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> >
> > ---
> > v1->v2:
> > Implement the logic in xhci_queue_isoc_tx_prepare() instead of
> > a seperated function as suggested by Mathias.
> >
> > ---
> >   drivers/usb/host/xhci-ring.c | 32 ++++++--------------------------
> >   1 file changed, 6 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> > index fa83625..8edc286 100644
> > --- a/drivers/usb/host/xhci-ring.c
> > +++ b/drivers/usb/host/xhci-ring.c
> [...]
> > @@ -3983,10 +3961,12 @@ int xhci_queue_isoc_tx_prepare(struct 
> > xhci_hcd *xhci, gfp_t mem_flags,
> >       }
> >
> >       /* 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)) {
> > +        if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK)
> > +                    == EP_STATE_RUNNING &&
> > +                !list_empty(&ep_ring->td_list))
> > +            urb->start_frame = xep->next_frame_id;
> > +            goto skip_start_over;
>
>    Forgot {}?

Oh, I am sorry. I am wondering how it passed my test.

I will send v3 patch soon any way.

> >       }
> >
> >       start_frame = readl(&xhci->run_regs->microframe_index);
>
> MBR, Sergei
>
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