Re: [PATCH 04/12] phylib: add a way to make PHY time stamps possible.
From: Grant Likely <hidden>
Date: 2010-06-15 16:33:51
Also in:
linux-arm-kernel, linux-devicetree, netdev
On Tue, Jun 15, 2010 at 10:08 AM, Richard Cochran [off-list ref] wrote:
This patch adds a new networking option to allow hardware time stamps from PHY devices. Using PHY time stamps will still require adding two inline function calls to each MAC driver. The CONFIG option makes these calls safe to add, since the calls become NOOPs when the option is disabled. Signed-off-by: Richard Cochran <redacted> --- =A0include/linux/phy.h =A0 =A0| =A0 =A04 ++++ =A0include/linux/skbuff.h | =A0 32 ++++++++++++++++++++++++++++++++ =A0net/Kconfig =A0 =A0 =A0 =A0 =A0 =A0| =A0 11 +++++++++++ =A03 files changed, 47 insertions(+), 0 deletions(-)
[...]
quoted hunk
diff --git a/net/Kconfig b/net/Kconfig index 0d68b40..3fa7ae3 100644 --- a/net/Kconfig +++ b/net/Kconfig@@ -86,6 +86,17 @@ config NETWORK_SECMARK=A0 =A0 =A0 =A0 =A0to nfmark, but designated for security purposes. =A0 =A0 =A0 =A0 =A0If you are unsure how to answer this question, answer =
N.
+config NETWORK_PHY_TIMESTAMPING + =A0 =A0 =A0 bool "Timestamping in PHY devices" + =A0 =A0 =A0 depends on EXPERIMENTAL + =A0 =A0 =A0 help + =A0 =A0 =A0 =A0 This allows timestamping of network packets by PHYs wit=
h
+ =A0 =A0 =A0 =A0 hardware timestamping capabilities. This option adds so=
me
+ =A0 =A0 =A0 =A0 overhead in the transmit and receive paths. Note that t=
his
+ =A0 =A0 =A0 =A0 option also requires support in the MAC driver.
Some overhead? At a brief glance of the series it looks like it could add a lot of overhead, but I'm not fully clear on what the full process is. Can you describe how the hardware timestamping works? I could use an overview of what the kernel has to do. g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.