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From: Greg KH <>
To: Jim Lin <>
Subject: Re: [PATCH v11 0/2] usb: xhci: Add Clear_TT_Buffer
Date: Mon, 3 Jun 2019 14:23:03 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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?

> Signed-off-by: Jim Lin <>

There is nothing to sign off on a 0/X patch :)


greg k-h

  parent reply	other threads:[~2019-06-03 12:23 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-03 10:53 Jim Lin
2019-06-03 10:53 ` [PATCH v11 1/2] usb: Add devaddr in struct usb_device Jim Lin
2019-06-05  9:48   ` Jim Lin
2019-06-03 10:53 ` [PATCH v11 2/2] usb: xhci: Add Clear_TT_Buffer Jim Lin
2019-06-03 12:35   ` Mathias Nyman
2019-06-03 12:23 ` Greg KH [this message]
2019-06-04  8:53   ` [PATCH v11 0/2] " Jim Lin
2019-06-04  8:59     ` Greg KH
2019-06-04 14:22     ` Alan Stern
  -- strict thread matches above, loose matches on Subject: below --
2019-05-29 14:55 Jim Lin

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