netdev - [PATCH V3 00/10] net: expand time stamping, batch #1

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Date:	Sun, 12 Jun 2011 14:18:57 +0200
From:	Richard Cochran <richardcochran@...il.com>
To:	<netdev@...r.kernel.org>
Cc:	David Miller <davem@...emloft.net>
Subject: [PATCH V3 00/10] net: expand time stamping, batch #1

This patch series represents the start of an effort to get better
coverage of the SO_TIMESTAMPING socket API in the Ethernet drivers.
Adding time stamping support to a given driver solves two separate
issues, namely software transmit time stamping and hardware time
stamping in PHY devices.

The SO_TIMESTAMPING socket API has been around since 2.6.30, but it
turned out that getting software transmit time stamps could not be
done in one central place in the stack. Instead, a work around was
introduced whereby each MAC driver must call a skb_tx_timestamp() hook
in order to support SW Tx time stamps.

Full PTP Hardware Clock (PHC) support has been merged for Linux 3.0,
including a driver for a PHY that does HW stamping. In the receive
path, the PHY based time stamping is handled by the stack for NAPI
based MAC drivers. But for transmit time stamps, support is needed in
the Ethernet MAC driver by calling the skb_tx_timestamp() hook.

The first patch exports a time stamping function for use in modules.
The next three patches enable PHY time stamping for two MACs which
have been paired with a PHC PHY on real life boards.

The remaining patches are for MACs that I chose because they (1) use
phylib and (2) compile for x86. However, I only compiled these, not
tested, since I do not have the hardware.

The larger goal is to eventually get the skb_tx_timestamp hook into as
many Ethernet MAC drivers as possible, so that SO_TIMESTAMPING using
SW time stamps will be supported across on most modern hardware. I
have started by picking those drivers in which adding the hook will
bring the greatest benefit, namely those using phylib, since adding
hooks provides both SW and PHY HW time stamping.

If people approve of this effort, I will follow with another patch
series adding SW Tx time stamping to yet more MACs. Adding SW Tx
support is just a single line, but still, perhaps compile testing only
is too risky. I would appreciate feedback on this issue.

Richard Cochran (10):
  net: export time stamp utility function for Ethernet MAC drivers
  fec: enable transmit and receive time stamping.
  davinci_emac: pass ioctls through to phy device.
  davinci_emac: enable transmit time stamping.
  tg3: enable transmit time stamping.
  dnet: enable transmit time stamping.
  ethoc: enable transmit time stamping.
  r6040: enable transmit time stamping.
  stmmac: enable transmit time stamping.
  smsc9420: enable transmit time stamping.

 drivers/net/davinci_emac.c       |    5 +++--
 drivers/net/dnet.c               |    2 ++
 drivers/net/ethoc.c              |    1 +
 drivers/net/fec.c                |    5 ++++-
 drivers/net/r6040.c              |    2 ++
 drivers/net/smsc9420.c           |    2 ++
 drivers/net/stmmac/stmmac_main.c |    2 ++
 drivers/net/tg3.c                |    2 ++
 net/core/timestamping.c          |    1 +
 9 files changed, 19 insertions(+), 3 deletions(-)

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