Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932499AbdGXVEL (ORCPT ); Mon, 24 Jul 2017 17:04:11 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:57745 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756183AbdGXVEB (ORCPT ); Mon, 24 Jul 2017 17:04:01 -0400 Date: Mon, 24 Jul 2017 14:03:58 -0700 From: Guenter Roeck To: Alan Stern Cc: Zdenek Kabelac , LKML , dianders@chromium.org, gregkh@linuxfoundation.org Subject: Re: USB disk speed regression WD Elements - with bisect result 22547c4cc4fe20698a6a85a55b8788859134b8e4 Message-ID: <20170724210358.GC31959@roeck-us.net> References: <0759ca4b-8f0b-1b3e-5073-19433795f325@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1743 Lines: 46 On Mon, Jul 24, 2017 at 10:41:12AM -0400, Alan Stern wrote: > On Mon, 24 Jul 2017, Zdenek Kabelac wrote: > > > Hi > > > > I've problem with my USB storage devices: WD Elements 1TB. > > (Bus 004 Device 002: ID 1058:10a8 Western Digital Technologies, Inc. Elements > > Portable (WDBUZG)) > > > > > > After kernel >4.9 when disk is attached via cable it has very low speed > > (less then 1MB/s). > > > > It can run at full speed (>22MB/s) when the Linux kernel is fully rebooted (so > > disk is attached during the reboot of Lenovo T61, C2D, Fedora Rawhide). > > > > However when >4.9 kernel is running and disk is just attached it's very slow. > > > > I've played a bisect game - and the clean result has been: > > > > 22547c4cc4fe20698a6a85a55b8788859134b8e4 > > > > When I just revert this patch with 4.13-rc1 - it's again running with full > > speed even when disk is attached (thus no reboot is needed for full speed). > > > > > > So while I've no idea what 22547c4cc4fe20698... is doing, it seems to have > > some unpleasant side-effect on regular USB devices. > > > > So what else is needed to get this properly working ? > > (assuming plain revert of 22547c4cc4fe20698 is unwanted). > > > > What more info can I provide to get this storage 'normally' usable without > > rebooting the machine. > > Please post the dmesg logs showing what happens when the disk is > first attached and operates slowly, and what happens when the disk is > attached following a reboot and operates normally. > Only idea I came up with is that some device may require more than one port reset. Agreed, dmesg logs should give us an idea if this is the case. I ordered one of those drives; maybe I can reproduce the problem. Guenter