Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 19 Oct 2018 10:05:52 -0400 (EDT)
From:   Alan Stern <stern@rowland.harvard.edu>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
cc:     gregkh@linuxfoundation.org, <linux-usb@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] USB: Wait for extra delay time after USB_PORT_FEAT_RESET
 for quirky hub
In-Reply-To: <20181019081450.21230-1-kai.heng.feng@canonical.com>
Message-ID: <Pine.LNX.4.44L0.1810191005380.1406-100000@iolanthe.rowland.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, 19 Oct 2018, Kai-Heng Feng wrote:

> Devices connected under Terminus Technology Inc. Hub (1a40:0101) may
> fail to work after the system resumes from suspend:
> [  206.063325] usb 3-2.4: reset full-speed USB device number 4 using xhci_hcd
> [  206.143691] usb 3-2.4: device descriptor read/64, error -32
> [  206.351671] usb 3-2.4: device descriptor read/64, error -32
> 
> Info for this hub:
> T:  Bus=03 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=480 MxCh= 4
> D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=01 MxPS=64 #Cfgs=  1
> P:  Vendor=1a40 ProdID=0101 Rev=01.11
> S:  Product=USB 2.0 Hub
> C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
> I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
> 
> Some expirements indicate that the USB devices connected to the hub are
> innocent, it's the hub itself is to blame. The hub needs extra delay
> time after it resets its port.
> 
> Hence wait for extra delay, if the device is connected to this quirky
> hub.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> v2:
>   - Use hub->hdev to check quirk.
>   - Merge the delay with TRSTRCY.

Acked-by: Alan Stern <stern@rowland.harvard.edu>