[PATCH net-next 00/10] net: stmmac: TSO fixes/cleanups

[Russell King (Oracle)]

Hot off the press from reading various sources of dwmac information,
this series attempts to fix the buggy hacks that were previously
merged, and clean up the code handling this.

I'm not sure whether "TSO" or "GSO" should be used to describe this
feature - although it primarily handles TCP, dwmac4 appears to also
be able to handle UDP.

In essence, this series adds a .ndo_features_check() method to handle
whether TSO/GSO can be used for a particular skbuff - checking which
queue the skbuff is destined for and whether that has TBS available
which precludes TSO being enabled on that channel.

I'm also adding a check that the header is smaller than 1024 bytes,
as documented in those sources which have TSO support - this is due
to the hardware buffering the header in "TSO memory" which I guess
is limited to 1KiB. I expect this test never to trigger, but if
the headers ever exceed that size, the hardware will likely fail.

I'm also moving the VLAN insertion for TSO packets into core code -
with the addition of .do_Features_check(), this can be done and
unnecessary code removed from the stmmac driver.

I've changed the hardware initialisation to always enable TSO support
on the channels even if the user requests TSO/GSO to be disabled -
this fixes another issue as pointed out by Jakub in a previous review
of the two patches (now patches 5 and 6.)

I'm moving the setup of the GSO features, cleaning those up, and
adding a warning if platform glue requests this to be enabled but the
hardware has no support. Hopefully this will never trigger if everyone
got the STMMAC_FLAG_TSO_EN flag correct.

Also move the "TSO supported" message to the new
stmmac_set_gso_features() function so keep all this TSO stuff together.

 drivers/net/ethernet/stmicro/stmmac/stmmac.h      |   3 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 135 ++++++++++++++--------
 2 files changed, 92 insertions(+), 46 deletions(-)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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