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    SubjectRe: [PATCH] usb: host: xhci-plat: Enable XHCI_SPURIOUS_SUCCESS quirk for xhci-plat
    On 6/26/2013 2:32 PM, Felipe Balbi wrote:
    > Hi,
    >
    > 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.
    >>
    >> 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;
    >> }
    > doesn't look like the correct way to do this. What if enabling that
    > quirk on hosts which don't have the quirk cause problems ?
    For a controller which does not have this issue will never get a
    spurious success for short packet ( and that too for only ISOCH).

    per this commit ad808333d Intel xhci: Ignore spurious successful event.

    This spurious successful event behavior isn't technically disallowed by
    the xHCI specification, so make the xHCI driver just ignore the spurious
    completion event.
    > I would suggest adding a platform_data which (in our case) dwc3 will
    > pass to xhci-plat. Then you can do proper revision detection of the
    > synopsys controller and set the quirk only on the failing hosts.
    >
    > BTW, do you have the STARS number for this errata ?
    No STARS number yet.


    Regards
    -George


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