From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753591AbaC3XgN (ORCPT ); Sun, 30 Mar 2014 19:36:13 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36476 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753130AbaC3XZE (ORCPT ); Sun, 30 Mar 2014 19:25:04 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Julius Werner" Date: Mon, 31 Mar 2014 00:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 168/200] usb: Make DELAY_INIT quirk wait 100ms between Get Configuration requests In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Julius Werner commit d86db25e53fa69e3e97f3b55dd82a70689787c5d upstream. The DELAY_INIT quirk only reduces the frequency of enumeration failures with the Logitech HD Pro C920 and C930e webcams, but does not quite eliminate them. We have found that adding a delay of 100ms between the first and second Get Configuration request makes the device enumerate perfectly reliable even after several weeks of extensive testing. The reasons for that are anyone's guess, but since the DELAY_INIT quirk already delays enumeration by a whole second, wating for another 10th of that isn't really a big deal for the one other device that uses it, and it will resolve the problems with these webcams. Signed-off-by: Julius Werner Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/core/config.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -722,6 +722,10 @@ int usb_get_configuration(struct usb_dev result = -ENOMEM; goto err; } + + if (dev->quirks & USB_QUIRK_DELAY_INIT) + msleep(100); + result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, bigbuffer, length); if (result < 0) {