Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751746AbdGZPEF (ORCPT ); Wed, 26 Jul 2017 11:04:05 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:49044 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751679AbdGZPED (ORCPT ); Wed, 26 Jul 2017 11:04:03 -0400 Date: Wed, 26 Jul 2017 11:04:02 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Zdenek Kabelac cc: Guenter Roeck , LKML , , Subject: Re: USB disk speed regression WD Elements - with bisect result 22547c4cc4fe20698a6a85a55b8788859134b8e4 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 790 Lines: 21 On Wed, 26 Jul 2017, Zdenek Kabelac wrote: > Well I do have 4.13-rc1 kernel - where the only difference is the revert > of mentioned patched - so I can provide probably traces from this one if that > helps anything. > > What is not quite clear to me - why T440 works. > > Could this be in some way related to the fact that T61 is USB2 only old lenovo > machine while T440 works with USB3 (new SuperSpeed USB device number...) Very likely that is the reason. The hardware is different. > So maybe there is some time-sensitive logic - where WD Elements > decides to be USB2 or USB3 device ??? The decision has to be agreed upon on both sides -- the drive and the kernel. If you enable debugging in the kernel, we'll have a better picture of what it is deciding to do. Alan Stern