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  1. 28 3月, 2020 1 次提交
    • V
      net: dsa: configure the MTU for switch ports · bfcb8132
      由 Vladimir Oltean 提交于 
      It is useful be able to configure port policers on a switch to accept
frames of various sizes:

- Increase the MTU for better throughput from the default of 1500 if it
  is known that there is no 10/100 Mbps device in the network.
- Decrease the MTU to limit the latency of high-priority frames under
  congestion, or work around various network segments that add extra
  headers to packets which can't be fragmented.

For DSA slave ports, this is mostly a pass-through callback, called
through the regular ndo ops and at probe time (to ensure consistency
across all supported switches).

The CPU port is called with an MTU equal to the largest configured MTU
of the slave ports. The assumption is that the user might want to
sustain a bidirectional conversation with a partner over any switch
port.

The DSA master is configured the same as the CPU port, plus the tagger
overhead. Since the MTU is by definition L2 payload (sans Ethernet
header), it is up to each individual driver to figure out if it needs to
do anything special for its frame tags on the CPU port (it shouldn't
except in special cases). So the MTU does not contain the tagger
overhead on the CPU port.
However the MTU of the DSA master, minus the tagger overhead, is used as
a proxy for the MTU of the CPU port, which does not have a net device.
This is to avoid uselessly calling the .change_mtu function on the CPU
port when nothing should change.

So it is safe to assume that the DSA master and the CPU port MTUs are
apart by exactly the tagger's overhead in bytes.

Some changes were made around dsa_master_set_mtu(), function which was
now removed, for 2 reasons:
  - dev_set_mtu() already calls dev_validate_mtu(), so it's redundant to
    do the same thing in DSA
  - __dev_set_mtu() returns 0 if ops->ndo_change_mtu is an absent method
That is to say, there's no need for this function in DSA, we can safely
call dev_set_mtu() directly, take the rtnl lock when necessary, and just
propagate whatever errors get reported (since the user probably wants to
be informed).

Some inspiration (mainly in the MTU DSA notifier) was taken from a
vaguely similar patch from Murali and Florian, who are credited as
co-developers down below.
Co-developed-by: NMurali Krishna Policharla <murali.policharla@broadcom.com>
Signed-off-by: NMurali Krishna Policharla <murali.policharla@broadcom.com>
Co-developed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      bfcb8132
  3. 04 3月, 2020 1 次提交
  5. 09 1月, 2020 1 次提交
    • F
      net: dsa: Get information about stacked DSA protocol · 4d776482
      由 Florian Fainelli 提交于 
      It is possible to stack multiple DSA switches in a way that they are not
part of the tree (disjoint) but the DSA master of a switch is a DSA
slave of another. When that happens switch drivers may have to know this
is the case so as to determine whether their tagging protocol has a
remove chance of working.

This is useful for specific switch drivers such as b53 where devices
have been known to be stacked in the wild without the Broadcom tag
protocol supporting that feature. This allows b53 to continue supporting
those devices by forcing the disabling of Broadcom tags on the outermost
switches if necessary.

The get_tag_protocol() function is therefore updated to gain an
additional enum dsa_tag_protocol argument which denotes the current
tagging protocol used by the DSA master we are attached to, else
DSA_TAG_PROTO_NONE for the top of the dsa_switch_tree.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4d776482
  7. 06 1月, 2020 1 次提交
    • V
      net: dsa: Make deferred_xmit private to sja1105 · a68578c2
      由 Vladimir Oltean 提交于 
      There are 3 things that are wrong with the DSA deferred xmit mechanism:

1. Its introduction has made the DSA hotpath ever so slightly more
   inefficient for everybody, since DSA_SKB_CB(skb)->deferred_xmit needs
   to be initialized to false for every transmitted frame, in order to
   figure out whether the driver requested deferral or not (a very rare
   occasion, rare even for the only driver that does use this mechanism:
   sja1105). That was necessary to avoid kfree_skb from freeing the skb.

2. Because L2 PTP is a link-local protocol like STP, it requires
   management routes and deferred xmit with this switch. But as opposed
   to STP, the deferred work mechanism needs to schedule the packet
   rather quickly for the TX timstamp to be collected in time and sent
   to user space. But there is no provision for controlling the
   scheduling priority of this deferred xmit workqueue. Too bad this is
   a rather specific requirement for a feature that nobody else uses
   (more below).

3. Perhaps most importantly, it makes the DSA core adhere a bit too
   much to the NXP company-wide policy "Innovate Where It Doesn't
   Matter". The sja1105 is probably the only DSA switch that requires
   some frames sent from the CPU to be routed to the slave port via an
   out-of-band configuration (register write) rather than in-band (DSA
   tag). And there are indeed very good reasons to not want to do that:
   if that out-of-band register is at the other end of a slow bus such
   as SPI, then you limit that Ethernet flow's throughput to effectively
   the throughput of the SPI bus. So hardware vendors should definitely
   not be encouraged to design this way. We do _not_ want more
   widespread use of this mechanism.

Luckily we have a solution for each of the 3 issues:

For 1, we can just remove that variable in the skb->cb and counteract
the effect of kfree_skb with skb_get, much to the same effect. The
advantage, of course, being that anybody who doesn't use deferred xmit
doesn't need to do any extra operation in the hotpath.

For 2, we can create a kernel thread for each port's deferred xmit work.
If the user switch ports are named swp0, swp1, swp2, the kernel threads
will be named swp0_xmit, swp1_xmit, swp2_xmit (there appears to be a 15
character length limit on kernel thread names). With this, the user can
change the scheduling priority with chrt $(pidof swp2_xmit).

For 3, we can actually move the entire implementation to the sja1105
driver.

So this patch deletes the generic implementation from the DSA core and
adds a new one, more adequate to the requirements of PTP TX
timestamping, in sja1105_main.c.
Suggested-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NVladimir Oltean <olteanv@gmail.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a68578c2
  9. 18 12月, 2019 1 次提交
  11. 24 11月, 2019 1 次提交
  13. 23 10月, 2019 1 次提交
  15. 10 7月, 2019 1 次提交
  17. 31 5月, 2019 1 次提交
  19. 30 5月, 2019 1 次提交
  21. 06 5月, 2019 1 次提交
    • V
      net: dsa: Add support for deferred xmit · 97a69a0d
      由 Vladimir Oltean 提交于 
      Some hardware needs to take work to get convinced to receive frames on
the CPU port (such as the sja1105 which takes temporary L2 forwarding
rules over SPI that last for a single frame). Such work needs a
sleepable context, and because the regular .ndo_start_xmit is atomic,
this cannot be done in the tagger. So introduce a generic DSA mechanism
that sets up a transmit skb queue and a workqueue for deferred
transmission.

The new driver callback (.port_deferred_xmit) is in dsa_switch and not
in the tagger because the operations that require sleeping typically
also involve interacting with the hardware, and not simply skb
manipulations. Therefore having it there simplifies the structure a bit
and makes it unnecessary to export functions from the driver to the
tagger.

The driver is responsible of calling dsa_enqueue_skb which transfers it
to the master netdevice. This is so that it has a chance of performing
some more work afterwards, such as cleanup or TX timestamping.

To tell DSA that skb xmit deferral is required, I have thought about
changing the return type of the tagger .xmit from struct sk_buff * into
a enum dsa_tx_t that could potentially encode a DSA_XMIT_DEFER value.

But the trailer tagger is reallocating every skb on xmit and therefore
making a valid use of the pointer return value. So instead of reworking
the API in complicated ways, right now a boolean property in the newly
introduced DSA_SKB_CB is set.
Signed-off-by: NVladimir Oltean <olteanv@gmail.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      97a69a0d
  23. 01 5月, 2019 2 次提交
  25. 29 4月, 2019 3 次提交
  27. 04 3月, 2019 1 次提交
  29. 25 2月, 2019 1 次提交
  31. 22 2月, 2019 2 次提交
  33. 18 1月, 2019 1 次提交
    • P
      net: Add extack argument to ndo_fdb_add() · 87b0984e
      由 Petr Machata 提交于 
      Drivers may not be able to support certain FDB entries, and an error
code is insufficient to give clear hints as to the reasons of rejection.

In order to make it possible to communicate the rejection reason, extend
ndo_fdb_add() with an extack argument. Adapt the existing
implementations of ndo_fdb_add() to take the parameter (and ignore it).
Pass the extack parameter when invoking ndo_fdb_add() from rtnl_fdb_add().
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      87b0984e
  35. 17 12月, 2018 1 次提交
  37. 13 9月, 2018 1 次提交
  39. 08 9月, 2018 1 次提交
  41. 12 5月, 2018 1 次提交
    • F
      net: dsa: Plug in PHYLINK support · aab9c406
      由 Florian Fainelli 提交于 
      Add support for PHYLINK within the DSA subsystem in order to support more
complex devices such as pluggable (SFP) and non-pluggable (SFF) modules, 10G
PHYs, and traditional PHYs. Using PHYLINK allows us to drop some amount of
complexity we had while probing fixed and non-fixed PHYs using Device Tree.

Because PHYLINK separates the Ethernet MAC/port configuration into different
stages, we let switch drivers implement those, and for now, we maintain
functionality by calling dsa_slave_adjust_link() during
phylink_mac_link_{up,down} which provides semantically equivalent steps.

Drivers willing to take advantage of PHYLINK should implement the phylink_mac_*
operations that DSA wraps.

We cannot quite remove the adjust_link() callback just yet, because a number of
drivers rely on that for configuring their "CPU" and "DSA" ports, this is done
dsa_port_setup_phy_of() and dsa_port_fixed_link_register_of() still.

Drivers that utilize fixed links for user-facing ports (e.g: bcm_sf2) will need
to implement phylink_mac_ops from now on to preserve functionality, since PHYLINK
*does not* create a phy_device instance for fixed links.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      aab9c406
  43. 08 4月, 2018 1 次提交
  45. 24 1月, 2018 1 次提交
  47. 03 1月, 2018 1 次提交
  49. 08 12月, 2017 1 次提交
  51. 13 11月, 2017 1 次提交
  53. 10 11月, 2017 1 次提交
  55. 09 11月, 2017 1 次提交
  57. 01 11月, 2017 1 次提交
  59. 28 10月, 2017 1 次提交
  61. 18 10月, 2017 4 次提交
  63. 01 10月, 2017 2 次提交