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SubjectRe: [PATCH] usb: host: xhci-plat: Enable XHCI_SPURIOUS_SUCCESS quirk for xhci-plat
On Wed, Jun 26, 2013 at 09:53:34AM -0700, Sarah Sharp wrote:
> On Wed, Jun 26, 2013 at 02:28:57PM +0530, George Cherian wrote:
> > Synopsis xhci controllers with hci_version > 0.96 gives spurious success
> > events on short packet completion. During webcam capture the
> > "ERROR Transfer event TRB DMA ptr not part of current TD" was observed.
> > The same application works fine with synopsis controllers hci_version 0.96.
>
> It's a known issue. The xHCI 1.0 spec changed how hardware handles
> short packets. The HW will notify SW of the TRB where the short packet,
> and it will also give a successful status for the last TRB in a TD (the
> one with the IOC flag set). On the second successful status, that
> warning will be triggered in the driver.
>
> Software is now supposed to not assume the TD as done until it gets that
> last successful status. That means we have a slight race condition,
> although it should have little practical impact. This patch papers over
> that issue.
>
> I will take this patch, but will add the note that is on my long-term
> to-do list to fix this issue.

Actually, since it applies to both xhci-plat and xhci-pci hosts, can you
move setting this quirk into xhci_gen_setup?

Sarah Sharp

> > Signed-off-by: George Cherian <george.cherian@ti.com>
> > ---
> > drivers/usb/host/xhci-plat.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > index 93ad67e..e63c6d3 100644
> > --- a/drivers/usb/host/xhci-plat.c
> > +++ b/drivers/usb/host/xhci-plat.c
> > @@ -25,6 +25,16 @@ static void xhci_plat_quirks(struct device *dev, struct xhci_hcd *xhci)
> > * dev struct in order to setup MSI
> > */
> > xhci->quirks |= XHCI_BROKEN_MSI;
> > +
> > + /*
> > + * In some xhci controllers which follows xhci 1.0 spec gives a spurious
> > + * success event after a short transfer. This quirk will ignore such
> > + * spurious event. Hit this issue in synopsis xhci controllers with
> > + * hci_version > 0.96
> > + */
> > +
> > + if (xhci->hci_version > 0x96)
> > + xhci->quirks |= XHCI_SPURIOUS_SUCCESS;
> > }
> >
> > /* called during probe() after chip reset completes */
> > --
> > 1.8.1.4
> >
> --
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