Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753945AbdIFMeN (ORCPT ); Wed, 6 Sep 2017 08:34:13 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33958 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753545AbdIFMeJ (ORCPT ); Wed, 6 Sep 2017 08:34:09 -0400 X-Google-Smtp-Source: ADKCNb6XhepjqhnT+VUN6gUs2IeXRKceZ9jI0G0S++TjZh89e/kerZ9De/SSshzXGwBsvEZhDghhbg== Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH] usb: Increase quirk delay for USB devices From: Dmitry Fleytman In-Reply-To: <20170905202225.GC16996@roeck-us.net> Date: Wed, 6 Sep 2017 15:34:02 +0300 Cc: Greg Kroah-Hartman , Alan Stern , Samuel Thibault , Mathias Nyman , Johan Hovold , Geert Uytterhoeven , Eugene Korenevsky , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: References: <20170905084059.28816-1-dmitry@daynix.com> <20170905202225.GC16996@roeck-us.net> To: Guenter Roeck X-Mailer: Apple Mail (2.3273) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v86CYKdS028100 Content-Length: 2178 Lines: 71 > On 5 Sep 2017, at 23:22 PM, Guenter Roeck wrote: > > On Tue, Sep 05, 2017 at 11:40:56AM +0300, Dmitry Fleytman wrote: >> Commit e0429362ab15 >> ("usb: Add device quirk for Logitech HD Pro Webcams C920 and C930e") >> introduced quirk to workaround an issue with some Logitech webcams. >> >> The workaround is introducing delay for some USB operations. >> >> According to our testing, delay introduced by original commit >> is not long enough and in rare cases we still see issues described >> by the aforementioned commit. >> >> This patch increases delays introduced by original commit. >> Having this patch applied we do not see those problems anymore. >> >> Signed-off-by: Dmitry Fleytman >> --- >> drivers/usb/core/config.c | 2 +- >> drivers/usb/core/hub.c | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c >> index 4be52c6..854c8d6 100644 >> --- a/drivers/usb/core/config.c >> +++ b/drivers/usb/core/config.c >> @@ -852,7 +852,7 @@ int usb_get_configuration(struct usb_device *dev) >> } >> >> if (dev->quirks & USB_QUIRK_DELAY_INIT) >> - msleep(100); >> + msleep(200); > > How did you determine the new delays ? Was it discussed with the vendor, > or is it based on trial and error ? It was based in trial and error. > > Either case, did you confirm that you need to increase both delays > for the problem to disappear ? Yes, according to testing results on our setups. Thanks, Dmitry > > Thanks, > Guenter > >> >> result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, >> bigbuffer, length); >> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c >> index 822f8c5..78c2aca 100644 >> --- a/drivers/usb/core/hub.c >> +++ b/drivers/usb/core/hub.c >> @@ -4825,7 +4825,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus, >> goto loop; >> >> if (udev->quirks & USB_QUIRK_DELAY_INIT) >> - msleep(1000); >> + msleep(2000); >> >> /* consecutive bus-powered hubs aren't reliable; they can >> * violate the voltage drop budget. if the new child has >> -- >> 2.7.4