linux-kernel - Re: [PATCH] usb: xhci: Renesas uPD720202 needs short TX quirk

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Message-ID: <87fucpqotd.fsf@linux.intel.com>
Date:   Fri, 18 Aug 2017 11:10:06 +0300
From:   Felipe Balbi <felipe.balbi@...ux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Cc:     mathias.nyman@...el.com, gregkh@...uxfoundation.org,
        USB list <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: xhci: Renesas uPD720202 needs short TX quirk


Hi,

Kai-Heng Feng <kai.heng.feng@...onical.com> writes:
>>> When plugging Logitech C920 webcam, warning messages filled up dmesg:
>>> [77117.655018] xhci_hcd 0000:0c:00.0: WARN Successful completion on short TX: needs XHCI_TRUST_TX_LENGTH quirk?
>>> [77117.659018] xhci_hcd 0000:0c:00.0: WARN Successful completion on short TX: needs XHCI_TRUST_TX_LENGTH quirk?
>>
>> have you confirmed this is needed for this controller?
> I just found commit d2f48f05cd2a2 ("usb: xhci: ASMedia ASM1042A
> chipset need shorts TX quirk") and did the same thing for this
> controller.
>
>> Anybody from Renesas has confirmed it?
> No, it's a user reported problem, please check the bug report in the link.
>
>> Do you have an errata document to refer to?
> No. Probably need Renesas guy to provide it.

or confirm it. Yoshihiro, do you know if this is needed?

>>> [77122.622952] handle_tx_event: 541 callbacks suppressed
>>>
>>> No more warning messages with XHCI_TRUST_TX_LENGTH applied.
>>>
>>> BugLink: https://bugs.launchpad.net/bugs/1710548
>>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>>> ---
>>>  drivers/usb/host/xhci-pci.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
>>> index 8071c8fdd15e..8566b43e19ba 100644
>>> --- a/drivers/usb/host/xhci-pci.c
>>> +++ b/drivers/usb/host/xhci-pci.c
>>> @@ -202,8 +202,10 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
>>>               xhci->quirks |= XHCI_BROKEN_STREAMS;
>>>       }
>>>       if (pdev->vendor == PCI_VENDOR_ID_RENESAS &&
>>> -                     pdev->device == 0x0015)
>>> +                     pdev->device == 0x0015) {
>>
>> unnecessary
>>
>>>               xhci->quirks |= XHCI_RESET_ON_RESUME;
>>> +             xhci->quirks |= XHCI_TRUST_TX_LENGTH;
>>
>>                 xhci->quirks |= XHCI_RESET_ON_RESUME |
>>                                 XHCI_TRUST_TX_LENGTH;
>>
>>> +     }
>>
>> unnecessary
>
> Do you mean that this quirk just hide the warning, it doesn't fix the
> root cause?

no, I meant that you need to add {} if you make a single statement out
of the quirks.

-- 
balbi