linux-kernel - Re: [PATCH v11 0/2] usb: xhci: Add Clear_TT

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Date:   Tue, 4 Jun 2019 16:53:54 +0800
From:   Jim Lin <jilin@...dia.com>
To:     Greg KH <gregkh@...uxfoundation.org>, <stern@...land.harvard.edu>
CC:     <mathias.nyman@...el.com>, <kai.heng.feng@...onical.com>,
        <drinkcat@...omium.org>, <Thinh.Nguyen@...opsys.com>,
        <nsaenzjulienne@...e.de>, <jflat@...omium.org>, <malat@...ian.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 0/2] usb: xhci: Add Clear_TT_Buffer



On 2019年06月03日 20:23, Greg KH wrote:
> On Mon, Jun 03, 2019 at 06:53:42PM +0800, Jim Lin wrote:
>> USB 2.0 specification chapter 11.17.5 says "as part of endpoint halt
>> processing for full-/low-speed endpoints connected via a TT, the host
>> software must use the Clear_TT_Buffer request to the TT to ensure
>> that the buffer is not in the busy state".
>>
>> In our case, a full-speed speaker (ConferenceCam) is behind a high-
>> speed hub (ConferenceCam Connect), sometimes once we get STALL on a
>> request we may continue to get STALL with the folllowing requests,
>> like Set_Interface.
>>
>> Solution is to invoke usb_hub_clear_tt_buffer() to send
>> Clear_TT_Buffer request to the hub of the device for the following
>> Set_Interface requests to the device to get ACK successfully.
>>
>> The Clear_TT_Buffer request sent to the hub includes the address of
>> the LS/FS child device in wValue field. usb_hub_clear_tt_buffer()
>> uses udev->devnum to set the address wValue. This won't work for
>> devices connected to xHC.
>>
>> For other host controllers udev->devnum is the same as the address of
>> the usb device, chosen and set by usb core. With xHC the controller
>> hardware assigns the address, and won't be the same as devnum.
>>
>> Here we have two patches.
>> One is to add devaddr in struct usb_device for
>> usb_hub_clear_tt_buffer() to use.
>> Another is to invoke usb_hub_clear_tt_buffer() for halt processing.
> Why did you resend patch series 11?
Didn't get response in 2 or 3 days.
Will be more patient next time.

May I get patch v11 1/2 acked or reviewed by Alan?

Thanks,
Jim