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

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Date:   Fri, 18 Aug 2017 16:06:28 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Felipe Balbi <felipe.balbi@...ux.intel.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,

On Fri, Aug 18, 2017 at 3:22 PM, Felipe Balbi
<felipe.balbi@...ux.intel.com> wrote:
>
> 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.

>
>> [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?

>
> --
> balbi