From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [PATCH 0/6] net: qmi_wwan: MDM9x30 support Date: Thu, 03 Dec 2015 13:36:56 -0600 Message-ID: <1449171416.21472.42.camel@redhat.com> References: <1449167063-22703-1-git-send-email-bjorn@mork.no> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-usb@vger.kernel.org, Marcel Holtmann , Oliver Neukum , Aleksander Morgado To: =?ISO-8859-1?Q?Bj=F8rn?= Mork , netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48294 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753005AbbLCTg6 (ORCPT ); Thu, 3 Dec 2015 14:36:58 -0500 In-Reply-To: <1449167063-22703-1-git-send-email-bjorn@mork.no> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2015-12-03 at 19:24 +0100, Bj=C3=B8rn Mork wrote: > We add new device IDs all the time, often without any testing on > actual hardware. This is usually OK as long as the device is similar > to already supported devices, using the same chipset and firmware > basis. But the Sierra Wireless MC7455 is an example of a new chipset > generation. Adding it based on assumed similarity with its ancestors > proved too optimistic. >=20 > This series adds the missing bits and pieces necessary to support LTE > Advanced modems based on the Qualcomm MDM9x30 chipset. A big thanks > to > Sierra Wireless for providing MC7455 samples for testing >=20 > The most important change is the "raw-ip" support. The series also > adds a necessary control request, removes an unsupported device ID, > and adds a driver specific entry in MAINTAINERS. >=20 > A few random notes about "raw-ip": >=20 > "I rather have these all running in raw IP mode. The 802.3 framing is > utterly stupid." - Marcel Holtmann in Jan 2012 [1] >=20 > Marcel was right. I should have listened to him. What more can I > say? The decision was less clear-cut at the time, since all the devices did support 802.3 framing and DHCP. And people wanted easy-1-2-3 DHCP and bridging capability too. We still get a lot of people asking about issues with DHCP and even bridging. 802.3 makes it *look* simple but of course we know it's not that simple... > The 802.3 framing has provided a steady supply of firmware bugs for > many years. We've added driver workarounds for many of these, but > there are still known bugs where the workaround is so yucky that we > have refused to apply it. But all that is over now. The latest > generation Qualcomm chips no longer supports 802.3 framing at all. >=20 > I had two open questions regarding the "raw-ip" userspace API: >=20 > 1) Should we continue faking an ethernet device, even if we don't use > the L2 headers on the USB link anymore? >=20 > There was a vote in favour of the "headerless" device. This is the > honest representation of the hardware/firmware interface. I like the approach of the current patchset where it's more like a tun device. Simple. > 2) What input should the driver base its framing on? >=20 > Snooping or directly manipulating QMI is considered out of the > question. We delegated all QMI handling to userspace from the > beginning. >=20 > We have so far required userspace to configure the firmware for > "802.3" framing, or fail if that proved impossible. This > requirement is now changed. Userspace must now inform the driver > if it negotiates "raw-ip" framing. Two alternative interfaces > were > proposed: > - ethtool private driver flag, or > - sysfs file >=20 > The NetworkManager/ModemManager developers were in favour of the > sysfs alternative. Sysfs is the easiest for most things to touch; ethtool requires being able to do ioctls and bit operations or shell out to ethtool. Just stating the reasons for my above vote. Dan > These questions (or any other you migh have :) are of course still > open. This patch set presents the solutions I currently prefer, > considering the above. >=20 > All comments are appreciated, even simple '+1' ones. >=20 >=20 > Bj=C3=B8rn >=20 > [1] http://www.spinics.net/lists/linux-usb/msg57056.html >=20 >=20 > Bj=C3=B8rn Mork (6): > net: qmi_wwan: MDM9x30 specific power management > net: qmi_wwan: remove 1199:9070 device id > usbnet: allow mini-drivers to consume L2 headers > net: qmi_wwan: support "raw IP" mode > net: qmi_wwan: document the qmi/raw_ip sysfs file > MAINTAINERS: add qmi_wwan driver entry >=20 > Documentation/ABI/testing/sysfs-class-net-qmi | 23 +++++ > MAINTAINERS | 7 ++ > drivers/net/usb/qmi_wwan.c | 138 > +++++++++++++++++++++++++- > drivers/net/usb/usbnet.c | 5 +- > 4 files changed, 169 insertions(+), 4 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-class-net-qmi >=20