From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932827AbcHUQBL (ORCPT ); Sun, 21 Aug 2016 12:01:11 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:55588 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932601AbcHUPdg (ORCPT ); Sun, 21 Aug 2016 11:33:36 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?latin1?q?Bj=F8rn=20Mork?= , "David S . Miller" , Greg Kroah-Hartman , Willy Tarreau Subject: [PATCH 3.10 119/180] cdc_ncm: workaround for EM7455 "silent" data interface Date: Sun, 21 Aug 2016 17:30:49 +0200 Message-Id: <1471793510-13022-120-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1471793510-13022-1-git-send-email-w@1wt.eu> References: <1471793510-13022-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=latin1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bjørn Mork commit c086e7096170390594c425114d98172bc9aceb8a upstream. Several Lenovo users have reported problems with their Sierra Wireless EM7455 modem. The driver has loaded successfully and the MBIM management channel has appeared to work, including establishing a connection to the mobile network. But no frames have been received over the data interface. The problem affects all EM7455 and MC7455, and is assumed to affect other modems based on the same Qualcomm chipset and baseband firmware. Testing narrowed the problem down to what seems to be a firmware timing bug during initialization. Adding a short sleep while probing is sufficient to make the problem disappear. Experiments have shown that 1-2 ms is too little to have any effect, while 10-20 ms is enough to reliably succeed. Reported-by: Stefan Armbruster Reported-by: Ralph Plawetzki Reported-by: Andreas Fett Reported-by: Rasmus Lerdorf Reported-by: Samo Ratnik Reported-and-tested-by: Aleksander Morgado Signed-off-by: Bjørn Mork Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- drivers/net/usb/cdc_ncm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 6ee9665..a580241 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -477,6 +477,13 @@ advance: if (cdc_ncm_setup(ctx)) goto error2; + /* Some firmwares need a pause here or they will silently fail + * to set up the interface properly. This value was decided + * empirically on a Sierra Wireless MC7455 running 02.08.02.00 + * firmware. + */ + usleep_range(10000, 20000); + /* configure data interface */ temp = usb_set_interface(dev->udev, iface_no, data_altsetting); if (temp) -- 2.8.0.rc2.1.gbe9624a