From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755826AbcGFU1r (ORCPT ); Wed, 6 Jul 2016 16:27:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:60246 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755805AbcGFU1q (ORCPT ); Wed, 6 Jul 2016 16:27:46 -0400 Subject: Re: [v4.2-rc1 Regression] usb: Enable LPM for USB 2.01+ full-speed devices To: Alan Stern References: Cc: Greg KH , rtatiya@codeaurora.org, Robert Ancell , "mathias.nyman@linux.intel.com" , chasemetzger15@gmail.com, baolu.lu@linux.intel.com, oneukum@suse.com, kborer@gmail.com, jun.li@freescale.com, USB list , LKML From: Joseph Salisbury Message-ID: <577D69BD.3070809@canonical.com> Date: Wed, 6 Jul 2016 16:27:41 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/28/2016 11:40 AM, Alan Stern wrote: > On Tue, 28 Jun 2016, Joseph Salisbury wrote: > >> On 06/24/2016 08:06 AM, Joseph Salisbury wrote: >>> On 06/22/2016 12:14 PM, Greg KH wrote: >>>> On Wed, Jun 22, 2016 at 11:38:43AM -0400, Joseph Salisbury wrote: >>>>> Hi Rupesh, >>>>> >>>>> A kernel bug report was opened against Ubuntu [0]. After a kernel >>>>> bisect, it was found that reverting the following commit resolved this bug: >>>>> >>>>> commit a8425292816ceaa8c49e29d2114e85d85a73e080 >>>>> Author: Rupesh Tatiya >>>>> Date: Tue Apr 14 16:36:55 2015 +0530 >>>>> >>>>> usb: Enable LPM for USB 2.01+ full-speed devices >>>>> >>>>> >>>>> The regression was introduced as of v4.2-rc1. >>>>> >>>>> I was hoping to get your feedback, since you are the patch author. Do >>>>> you think gathering any additional data will help diagnose this issue, >>>>> or would it be best to submit a revert request? >>>> Does the problem still happen with 4.7-rc4 or even 4.6? >>>> >>>> 4.2 is pretty old and obsolete you know :) >>>> >>>> thanks, >>>> >>>> greg k-h >>> The regression does exist in 4.6-rc2. I'll have the latest mainline >>> 4.7-rc4 kernel tested. >> The 4.7-rc4 kernel still exhibits the bug. > Have you tried adding a NO_LPM quirk entry for this device, as I > suggested in an earlier email? I can write a patch for this, if you > want. > > Alan Stern > Yes, adding a NO_LPM quirk entry resolves the bug. I'll submit a patch shortly, it is basically these lines added to usb_quirk_list[]: + /* ELAN Microelectronics Touchscreen */ + { USB_DEVICE(0x04f3, 0x0381), .driver_info = USB_QUIRK_NO_LPM }, Thanks for the suggestion, Alan!