Many newer NCM and MBIM devices will request a maximum tx
datagram count which is much smaller than our hard-coded
absolute max. We can reduce the overhead without sacrificing
any of the simplicity for these devices, by simply using the
true negotiated count in when calculated the maximum NTH and
NDP header sizes.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Datagram coalescing is an integral part of the NCM and MBIM
protocols, intended to reduce the interrupt load primarily
on the device end of the USB link.  As with all coalescing
solutions, there is a trade-off between buffering and
interrupts.

The current defaults are based on the assumption that device
side buffers should be the limiting factor.  However, many
modern high speed LTE modems suffers from buffer-bloat,
making this assumption fail. This results in sub-optimal
performance due to excessive coalescing.  And in cases where
such modems are connected to cheap embedded hosts there is
often severe buffer allocation issues, giving very noticeable
performance degradation .

A start on improving this is going from build time hard
coded limits to per device user configurable limits.  The
ethtool coalescing API was selected as user interface
because, although the tuned values are buffer sizes, these
settings directly control datagram coalescing.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The NCM class match in the cdc_mbim driver is confusing and
cause unexpected behaviour. The USB core guarantees that a
USB interface is in altsetting 0 when probing starts. This
means that devices implementing a NCM 1.0 backwards
compatible MBIM function (a "NCM/MBIM function") always hit
the NCM entry in the cdc_mbim driver match table. Such
functions will never match any of the MBIM entries.

This causes unexpeced behaviour for cases where the NCM and
MBIM entries are differet, which is currently the case for
all except Ericsson devices.

Improve the probing of NCM/MBIM functions by looking up the
device again in the cdc_mbim match table after switching to
the MBIM identity.

The shared altsetting selection is updated to better
accommodate the new probing logic, returning the preferred
altsetting for the control interface instead of the data
interface. The control interface altsetting update is moved
to the cdc_mbim driver. It is never necessary to change the
control interface altsetting for NCM.

Cc: Greg Suarez <gsuarez@smithmicro.com>
Reported by: Yu-an Shih <yshih@nvidia.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

According to "Universal Serial Bus Communications Class Subclass
Specification for Mobile Broadband Interface Model, Revision 1.0,
Errata-1" published by USB-IF, the wMTU field of the MBIM extended
functional descriptor indicates the operator preferred MTU for IP data
streams.

This patch modifies cdc_ncm_setup to ensure that the MTU value set on
the usbnet device does not exceed the operator preferred MTU indicated
by wMTU if the MBIM device exposes a MBIM extended functional
descriptor.
Signed-off-by: NBen Chan <benchan@chromium.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is a context modified revert of commit 6a9612e2
("net: cdc_ncm: remove ncm_parm field") which introduced
a NCM specification violation, causing setup errors for
some devices. These errors resulted in the device and
host disagreeing about shared settings, with complete
failure to communicate as the end result.

The NCM specification require that many of the NCM specific
control reuests are sent only while the NCM Data Interface
is in alternate setting 0. Reverting the commit ensures that
we follow this requirement.

Fixes: 6a9612e2 ("net: cdc_ncm: remove ncm_parm field")
Reported-and-tested-by: NPasi Kärkkäinen <pasik@iki.fi>
Reported-by: NThomas Schäfer <tschaefer@t-online.de>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some drivers implementing NCM-like protocols, may re-use those functions, as is
the case in the huawei_cdc_ncm driver.
Export them via EXPORT_SYMBOL_GPL, in accordance with how other functions have
been exported.
Signed-off-by: NEnrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

header_desc was completely unused and union_desc was never used
outside cdc_ncm_bind_common.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Moving the call to cdc_ncm_setup() after the endpoint
setup removes the last remaining reference to ncm_parm
outside cdc_ncm_setup.

Collecting all the ncm_parm based calculations in
cdc_ncm_setup improves readability.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These fields are only used to prevent printing the same speeds
multiple times if we receive multiple identical speed notifications.

The value of these printk's is questionable, and even more so when
we filter out some of the notifications sent us by the firmware. If
we are going to print any of these, then we should print them all.

Removing little used fields is a bonus.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We already use the usbnet udev field everywhere this could have
been used.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Too many pointers back and forth are likely to confuse developers,
creating subtle bugs whenever we forget to syncronize them all.

As a usbnet driver, we should stick with the standard struct
usbnet fields as much as possible.  The netdevice is one such
field.

Cc: Greg Suarez <gsuarez@smithmicro.com>
Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

No need to duplicate stuff already in the common usbnet
struct.  We still need to keep our special find_endpoints
function because we need explicit control over the selected
altsetting.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is always a duplicate of the "control" field. It causes
confusion wrt intf_data updates and cleanups.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This makes it a lot easier to test modified versions

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit bd329e12 ("net: cdc_ncm: do not bind to NCM compatible MBIM devices")
introduced a new policy, preferring MBIM for dual NCM/MBIM functions if
the cdc_mbim driver was enabled.  This caused a regression for users
wanting to use NCM.

Devices implementing NCM backwards compatibility according to section
3.2 of the MBIM v1.0 specification allow either NCM or MBIM on a single
USB function, using different altsettings.  The cdc_ncm and cdc_mbim
drivers will both probe such functions, and must agree on a common
policy for selecting either MBIM or NCM.  Until now, this policy has
been set at build time based on CONFIG_USB_NET_CDC_MBIM.

Use a module parameter to set the system policy at runtime, allowing the
user to prefer NCM on systems with the cdc_mbim driver.

Cc: Greg Suarez <gsuarez@smithmicro.com>
Cc: Alexey Orishko <alexey.orishko@stericsson.com>
Reported-by: NGeir Haatveit <nospam@haatveit.nu>
Reported-by: NTommi Kyntola <kynde@ts.ray.fi>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=54791Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The CDC Mobile Broadband Interface Model (MBIM) specification
extends CDC NCM by
 - removing the redundant ethernet header from the point-to-point
   USB channel
 - adding support for multiple IP (v4 and/or v6) sessions multiplexed
   on the same USB channel
 - adding a MBIM control channel encapsulated in CDC
 - adding Device Service Streams (DSS), which are non IP generic data
   streams multiplexed on the same USB channel as the IP sessions

MBIM devices are managed using the dedicated control channel, and no
data will flow on the data channel until a control session has been
established.  This driver has no knowledge of MBIM control messages.
It just exports the control channel to a /dev/cdc-wdmX character
device for userspace management applications. Such an application is
therefore required to use this driver.

This patch implements basic MBIM support, reusing the NCM and WDM driver
APIs, currently limited to IP sessions with SessionID 0. DSS and
multiplexed IP sessions are not yet supported.
Signed-off-by: NGreg Suarez <gsuarez@smithmicro.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Move symbols and definitons which can be shared with a
MBIM driver in a new header.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>