Adds support for setting up VF configuration.
Signed-off-by: NRaghu Vatsavayi <raghu.vatsavayi@caviumnetworks.com>
Signed-off-by: NDerek Chickles <derek.chickles@caviumnetworks.com>
Signed-off-by: NSatanand Burla <satananda.burla@caviumnetworks.com>
Signed-off-by: NFelix Manlunas <felix.manlunas@caviumnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adds support for cn23xx VF probe and registration.
Signed-off-by: NRaghu Vatsavayi <raghu.vatsavayi@caviumnetworks.com>
Signed-off-by: NDerek Chickles <derek.chickles@caviumnetworks.com>
Signed-off-by: NSatanand Burla <satananda.burla@caviumnetworks.com>
Signed-off-by: NFelix Manlunas <felix.manlunas@caviumnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adds support for CN23xx VF registers.
Signed-off-by: NRaghu Vatsavayi <raghu.vatsavayi@caviumnetworks.com>
Signed-off-by: NDerek Chickles <derek.chickles@caviumnetworks.com>
Signed-off-by: NSatanand Burla <satananda.burla@caviumnetworks.com>
Signed-off-by: NFelix Manlunas <felix.manlunas@caviumnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch modifies test_cgrp2_attach to use getopt so we can use standard
command line parsing.

It also adds an option to run the program in detach only mode. This does
not attach a new filter at the cgroup, but only runs the detach command.

Lastly, it changes the attach code to not detach and then attach. It relies
on the 'hotswap' behaviour of CGroup BPF programs to be able to change
in-place. If detach-then-attach behaviour needs to be tested, the example
can be run in detach only mode prior to attachment.
Signed-off-by: NSargun Dhillon <sargun@sargun.me>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The ethtool api {get|set}_settings is deprecated.
We move this driver to new api {get|set}_link_ksettings.
Signed-off-by: NPhilippe Reynes <tremyfr@gmail.com>
Acked-by: NRasesh Mody <Rasesh.Mody@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add an IFLA_XDP_FLAGS attribute that can be passed for setting up
XDP along with IFLA_XDP_FD, which eventually allows user space to
implement typical add/replace/delete logic for programs. Right now,
calling into dev_change_xdp_fd() will always replace previous programs.

When passed XDP_FLAGS_UPDATE_IF_NOEXIST, we can handle this more
graceful when requested by returning -EBUSY in case we try to
attach a new program, but we find that another one is already
attached. This will be used by upcoming front-end for iproute2 as
well.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Florian Fainelli says:

====================
net: phy: broadcom: Support for PHY counters

This patch series adds support for reading the Broadcom PHYs internal counters.

Changes in v3:

- fixed the allocation of priv->stats in bcm7xxx

Changes in v2:

- fixed modular build reported by kbuild

- constify array of stats
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Broadcom BCM7xxx internal PHYs can leverage the Broadcom PHY library
module PHY error counters helper functions, just implement the
appropriate PHY driver function calls to do so. We need to allocate some
storage space for our PHY statistics, and provide it to the Broadcom PHY
library, so do this in a specific probe function, and slightly wrap the
get_stats function call.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Broadcom PHYs expose a number of PHY error counters: receive errors,
false carrier sense, SerDes BER count, local and remote receive errors.
Add support code to allow retrieving these error counters. Since the
Broadcom PHY library code is used by several drivers, make it possible
for them to specify the storage for the software copy of the statistics.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rationale: The differences between Falcon and Siena are in many ways larger
 than those between Siena and EF10 (despite Siena being nominally "Falcon-
 architecture"); for instance, Falcon has no MCPU, so there is no MCDI.
 Removing Falcon support from the sfc driver should simplify the latter,
 and avoid the possibility of Falcon support being broken by changes to sfc
 (which are rarely if ever tested on Falcon, it being end-of-lifed hardware).

The sfc-falcon driver created in this changeset is essentially a copy of the
 sfc driver, but with Siena- and EF10-specific code, including MCDI, removed
 and with the "efx_" identifier prefix changed to "ef4_" (for "EFX 4000-
 series") to avoid collisions when both drivers are built-in.

This changeset removes Falcon from the sfc driver's PCI ID table; then in
 sfc I've removed obvious Falcon-related code: I removed the Falcon NIC
 functions, Falcon PHY code, and EFX_REV_FALCON_*, then fixed up everything
 that referenced them.

Also, increment minor version of both drivers (to 4.1).

For now, CONFIG_SFC selects CONFIG_SFC_FALCON, so that updating old configs
 doesn't cause Falcon support to disappear; but that should be undone at
 some point in the future.
Signed-off-by: NEdward Cree <ecree@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support for ethtool's '-r' command. Restarting
N-WAY negotiation can be useful to activate newly changed EEE
settings etc.
Signed-off-by: NYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Yuchung Cheng says:

====================
tcp: sender chronographs instrumentation

This patch set provides instrumentation on TCP sender limitations.
While developing the BBR congestion control, we noticed that TCP
sending process is often limited by factors unrelated to congestion
control: insufficient sender buffer and/or insufficient receive
window/buffer to saturate the network bandwidth. Unfortunately these
limits are not visible to the users and often the poor performance
is attributed to the congestion control of choice.

Thie patch aims to help users get the high level understanding of
where sending process is limited by, similar to the TCP_INFO design.
It is not to replace detailed kernel tracing and instrumentation
facilities.

In addition this patch set provide a new option to the timestamping
work to instrument these limits on application data unit. For exampe,
one can use SO_TIMESTAMPING and this patch set to measure the how
long a particular HTTP response is limited by small receive window.

Patch set was initially written by Francis Yan then polished
by Yuchung Cheng, with lots of help from Eric Dumazet and Soheil
Hassas Yeganeh.
====================
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch exports the sender chronograph stats via the socket
SO_TIMESTAMPING channel. Currently we can instrument how long a
particular application unit of data was queued in TCP by tracking
SOF_TIMESTAMPING_TX_SOFTWARE and SOF_TIMESTAMPING_TX_SCHED. Having
these sender chronograph stats exported simultaneously along with
these timestamps allow further breaking down the various sender
limitation.  For example, a video server can tell if a particular
chunk of video on a connection takes a long time to deliver because
TCP was experiencing small receive window. It is not possible to
tell before this patch without packet traces.

To prepare these stats, the user needs to set
SOF_TIMESTAMPING_OPT_STATS and SOF_TIMESTAMPING_OPT_TSONLY flags
while requesting other SOF_TIMESTAMPING TX timestamps. When the
timestamps are available in the error queue, the stats are returned
in a separate control message of type SCM_TIMESTAMPING_OPT_STATS,
in a list of TLVs (struct nlattr) of types: TCP_NLA_BUSY_TIME,
TCP_NLA_RWND_LIMITED, TCP_NLA_SNDBUF_LIMITED. Unit is microsecond.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch exports all the sender chronograph measurements collected
in the previous patches to TCP_INFO interface. Note that busy time
exported includes all the other sending limits (rwnd-limited,
sndbuf-limited). Internally the time unit is jiffy but externally
the measurements are in microseconds for future extensions.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch measures the amount of time when TCP runs out of new data
to send to the network due to insufficient send buffer, while TCP
is still busy delivering (i.e. write queue is not empty). The goal
is to indicate either the send buffer autotuning or user SO_SNDBUF
setting has resulted network under-utilization.

The measurement starts conservatively by checking various conditions
to minimize false claims (i.e. under-estimation is more likely).
The measurement stops when the SOCK_NOSPACE flag is cleared. But it
does not account the time elapsed till the next application write.
Also the measurement only starts if the sender is still busy sending
data, s.t. the limit accounted is part of the total busy time.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch measures the total time when the TCP stops sending because
the receiver's advertised window is not large enough. Note that
once the limit is lifted we are likely in the busy status if we
have data pending.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch measures TCP busy time, which is defined as the period
of time when sender has data (or FIN) to send. The time starts when
data is buffered and stops when the write queue is flushed by ACKs
or error events.

Note the busy time does not include SYN time, unless data is
included in SYN (i.e. Fast Open). It does include FIN time even
if the FIN carries no payload. Excluding pure FIN is possible but
would incur one additional test in the fast path, which may not
be worth it.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch implements the skeleton of the TCP chronograph
instrumentation on sender side limits:

	1) idle (unspec)
	2) busy sending data other than 3-4 below
	3) rwnd-limited
	4) sndbuf-limited

The limits are enumerated 'tcp_chrono'. Since a connection in
theory can idle forever, we do not track the actual length of this
uninteresting idle period. For the rest we track how long the sender
spends in each limit. At any point during the life time of a
connection, the sender must be in one of the four states.

If there are multiple conditions worthy of tracking in a chronograph
then the highest priority enum takes precedence over
the other conditions. So that if something "more interesting"
starts happening, stop the previous chrono and start a new one.

The time unit is jiffy(u32) in order to save space in tcp_sock.
This implies application must sample the stats no longer than every
49 days of 1ms jiffy.
Signed-off-by: NFrancis Yan <francisyyan@gmail.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the ability to query and set Energy Efficient Ethernet parameters
via ethtool for applicable devices.

This patch doesn't activate full EEE support in cpsw driver, but it
enables reading and writing EEE advertising settings. This way one
can disable advertising EEE for certain speeds.
Signed-off-by: NYegor Yefremov <yegorslists@googlemail.com>
Acked-by: NRami Rosen <roszenrami@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When we change MTU or the number of channels on a netvsc device we get the
following logged:

 hv_netvsc bf5edba8...: net device safe to remove
 hv_netvsc: hv_netvsc channel opened successfully
 hv_netvsc bf5edba8...: Send section size: 6144, Section count:2560
 hv_netvsc bf5edba8...: Device MAC 00:15:5d:1e:91:12 link state up

This information is useful as debug at most.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jiri Pirko says:

====================
mlxsw: couple of enhancements and fixes

Couple of enhancements and fixes from Ido.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We call bus->init() before allocating 'lag.mapping'. Change the order of
operations in removal path to reflect that.

This makes the error path of mlxsw_core_bus_device_register() symmetric
with mlxsw_core_bus_device_unregister().
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Without this rollback, the thermal zone is still registered during the
error path, whereas its private data is freed upon the destruction of
the underlying bus device due to the use of devm_kzalloc(). This results
in use after free.

Fix this by calling mlxsw_thermal_fini() from the appropriate place in
the error path.

Fixes: a50c1e35 ("mlxsw: core: Implement thermal zone")
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The shared buffer pools are containers whose size is used to calculate
the maximum usage for packets from / to a specific port / {port, PG/TC},
when dynamic threshold is employed.

While it's perfectly fine for the sum of the pools to exceed the maximum
size of the shared buffer, a single pool cannot.

Add a check when the pool size is set and forbid sizes larger than the
maximum size of the shared buffer.

Without the patch:
$ devlink sb pool set pci/0000:03:00.0 pool 0 size 999999999 thtype
dynamic
// No error is returned

With the patch:
$ devlink sb pool set pci/0000:03:00.0 pool 0 size 999999999 thtype
dynamic
devlink answers: Invalid argument
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to be able to limit the size of shared buffer pools, so query
the maximum size from the device during init.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The newly added switchib driver fails to link if MLXSW_PCI=m:

drivers/net/ethernet/mellanox/mlxsw/mlxsw_switchib.o: In function^Cmlxsw_sib_module_exit':
switchib.c:(.exit.text+0x8): undefined reference to `mlxsw_pci_driver_unregister'
switchib.c:(.exit.text+0x10): undefined reference to `mlxsw_pci_driver_unregister'
drivers/net/ethernet/mellanox/mlxsw/mlxsw_switchib.o: In function `mlxsw_sib_module_init':
switchib.c:(.init.text+0x28): undefined reference to `mlxsw_pci_driver_register'
switchib.c:(.init.text+0x38): undefined reference to `mlxsw_pci_driver_register'
switchib.c:(.init.text+0x48): undefined reference to `mlxsw_pci_driver_unregister'

The other two such sub-drivers have a dependency, so add the same one
here. In theory we could allow this driver if MLXSW_PCI is disabled,
but it's probably not worth it.

Fixes: d1ba5263 ("mlxsw: switchib: Introduce SwitchIB and SwitchIB silicon driver")
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If device_release_driver(&phydev->mdio.dev) is called, it releases all
resources belonging to the PHY device. Hence the subsequent call to
phy_led_triggers_unregister() will access already freed memory when
unregistering the LEDs.

Move the call to phy_led_triggers_unregister() before the possible call
to device_release_driver() to fix this.

Fixes: 2e0bc452 ("net: phy: leds: add support for led triggers on phy link state change")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Tested-by: NZach Brown <zach.brown@ni.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix comments, add some new, and make debugfs output consistent.
Signed-off-by: NPavel Machek <pavel@denx.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's a 'not' missing in one paragraph. Add it.

Fixes: 30070984 ("cgroup: add support for eBPF programs")
Signed-off-by: NDaniel Mack <daniel@zonque.org>
Reported-by: NRami Rosen <roszenrami@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jerome Brunet says:

====================
Fix OdroidC2 Gigabit Tx link issue

This patchset fixes an issue with the OdroidC2 board (DWMAC + RTL8211F).
The platform seems to enter LPI on the Rx path too often while performing
relatively high TX transfer. This eventually break the link (both Tx and
Rx), and require to bring the interface down and up again to get the Rx
path working again.

The root cause of this issue is not fully understood yet but disabling EEE
advertisement on the PHY prevent this feature to be negotiated.
With this change, the link is stable and reliable, with the expected
throughput performance.

The patchset adds options in the generic phy driver to disable EEE
advertisement, through device tree. The way it is done is very similar
to the handling of the max-speed property.

Changes since V2: [2]
 - Rename "eee-advert-disable" to "eee-broken-modes" to make the intended
   purpose of this option clear (flag broken configuration, not a
   configuration option)
 - Add DT bindings constants so the DT configuration is more user friendly
 - Submit to net-next instead of net.

Changes since V1: [1]
 - Disable the advertisement of EEE in the generic code instead of the
   realtek driver.

[1] : http://lkml.kernel.org/r/1479220154-25851-1-git-send-email-jbrunet@baylibre.com
[2] : http://lkml.kernel.org/r/1479742524-30222-1-git-send-email-jbrunet@baylibre.com
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJerome Brunet <jbrunet@baylibre.com>
Reviewed-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJerome Brunet <jbrunet@baylibre.com>
Tested-by: NYegor Yefremov <yegorslists@googlemail.com>
Tested-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds an option to disable EEE advertisement in the generic PHY
by providing a mask of prohibited modes corresponding to the value found in
the MDIO_AN_EEE_ADV register.

On some platforms, PHY Low power idle seems to be causing issues, even
breaking the link some cases. The patch provides a convenient way for these
platforms to disable EEE advertisement and work around the issue.
Signed-off-by: NJerome Brunet <jbrunet@baylibre.com>
Tested-by: NYegor Yefremov <yegorslists@googlemail.com>
Tested-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The dwmac4 IP can synthesized with 1-8 number of tx queues.
On an IP synthesized with DWC_EQOS_NUM_TXQ > 1, all txqueues are disabled
by default. For these IPs, the bitfield TXQEN is R/W.

Always enable tx queue 0. The write will have no effect on IPs synthesized
with DWC_EQOS_NUM_TXQ == 1.

The driver does still not utilize more than one tx queue in the IP.
Signed-off-by: NNiklas Cassel <niklas.cassel@axis.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add dependencies on the architectures that support these devices and
add compile test to ensure ongoing code build coverage.
Signed-off-by: NPeter Robinson <pbrobinson@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Also include the netdev list for convenience, as done elsewhere.
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

mlx4 stats are chaotic because a deferred work queue is responsible
to update them every 250 ms.

Even sampling stats every one second with "sar -n DEV 1" gives
variations like the following :

lpaa23:~# sar -n DEV 1 10 | grep eth0 | cut -c1-65
07:39:22         eth0 146877.00 3265554.00   9467.15 4828168.50
07:39:23         eth0 146587.00 3260329.00   9448.15 4820445.98
07:39:24         eth0 146894.00 3259989.00   9468.55 4819943.26
07:39:25         eth0 110368.00 2454497.00   7113.95 3629012.17  <<>>
07:39:26         eth0 146563.00 3257502.00   9447.25 4816266.23
07:39:27         eth0 145678.00 3258292.00   9389.79 4817414.39
07:39:28         eth0 145268.00 3253171.00   9363.85 4809852.46
07:39:29         eth0 146439.00 3262185.00   9438.97 4823172.48
07:39:30         eth0 146758.00 3264175.00   9459.94 4826124.13
07:39:31         eth0 146843.00 3256903.00   9465.44 4815381.97
Average:         eth0 142827.50 3179259.70   9206.30 4700578.16

This patch allows rx/tx bytes/packets counters being folded at the
time we need stats.

We now can fetch stats every 1 ms if we want to check NIC behavior
on a small time window. It is also easier to detect anomalies.

lpaa23:~# sar -n DEV 1 10 | grep eth0 | cut -c1-65
07:42:50         eth0 142915.00 3177696.00   9212.06 4698270.42
07:42:51         eth0 143741.00 3200232.00   9265.15 4731593.02
07:42:52         eth0 142781.00 3171600.00   9202.92 4689260.16
07:42:53         eth0 143835.00 3192932.00   9271.80 4720761.39
07:42:54         eth0 141922.00 3165174.00   9147.64 4679759.21
07:42:55         eth0 142993.00 3207038.00   9216.78 4741653.05
07:42:56         eth0 141394.06 3154335.64   9113.85 4663731.73
07:42:57         eth0 141850.00 3161202.00   9144.48 4673866.07
07:42:58         eth0 143439.00 3180736.00   9246.05 4702755.35
07:42:59         eth0 143501.00 3210992.00   9249.99 4747501.84
Average:         eth0 142835.66 3182165.93   9206.98 4704874.08
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It shold reserved sizeof(ipv6hdr) for geneve in ipv6 tunnel.

Fixes: c3ef5aa5 ('geneve: Merge ipv4 and ipv6 geneve_build_skb()')
Signed-off-by: NHaishuang Yan <yanhaishuang@cmss.chinamobile.com>
Acked-by: NPravin B Shelar <pshelar@ovn.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Florian Fainelli says:

====================
Documentation: net: phy: Improve documentation

This patch series addresses discussions and feedback that was recently received
on the mailing-list in the area of: flow control/pause frames, interpretation of
phy_interface_t and finally add some links to useful standards documents.

Changes in v3:

- add Timur's feedback into patch 3

Changes in v2:

- clarify a few things in the RGMII section, add a paragraph about common issues
  with RGMII delay mismatches
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add links to the IEEE 802.3-2008 document, and the RGMII v1.3 and v2.0
revisions of the standard.
Reviewed-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>