From: Hans Petter Selasky <>
Subject: Re: [Bug?] Control Transfers in xHCI
Date: Thu, 29 Jan 2015 21:00:04 +0100
> On 01/29/15 20:57, Chagin Dmitry wrote:
>> On Thu, Jan 29, 2015 at 04:04:03PM +0100, Hans Petter Selasky wrote:
>>> On 01/29/15 13:25, Kohji Okuno wrote:
>>>> Hi HPS,
>>>> I found a bug in xHCI device driver.
>>>> Acording to extensible-host-controler-interface-usb-xhci.pdf:"3.2.9
>>>> Control Transfers"...
>>>> A Data Stage TD consists of a Data Stage TRB followed by zero or more
>>>> Normal TRBs. If the data is not physically contiguous, Normal TRBs may
>>>> be chained to the Data Stage TRB.
>>>> But, in the current imprementation, when two or more TRBs are needed,
>>>> the device driver set XHCI_TRB_TYPE_DATA_STAGE to all TRBs.
>>>> This is the violation of the spec.
>>>> In my minor xHCI, I encountered strange bubble error in a control
>>>> transfer. After I changed as the following, I succeeded its control
>>>> transfer.
>>>> Would you check the following (****)?
>>> Hi Kohji,
>>> You are correct there is a bug, but your patch is not correct.
>>> In FreeBSD we allow SETUP and DATA stages to be done as separate jobs.
>>> That means at the entry of creating a new DATA chain, we need to check
>>> if it is there first DATA packet or not.
>>> Can you test the attached patch and see if it works for you?
>> patch is lost somewhere, Hans.
> Trying again.
> I think Kohji got it.
> --HPS

Hi, HPS,

Thank you for your commet.
I will test your patch next week.

 Kohji Okuno
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