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Subject[PATCH net-next v3 0/4] Improve phc2sys precision for mv88e6xxx switch in combination with imx6-fec
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From: Hubert Feurstein <h.feurstein@gmail.com>

Changelog:
v3: mv88e6xxx_smi_indirect_write: forward ptp_sts only on the last write
Copied Miroslav Lichvar because of PTP offset compensation patch
v2: Added patch for PTP offset compensation
Removed mdiobus_write_sts as there was no user
Removed ptp_sts_supported-boolean and introduced flags instead

With this patchset the phc2sys synchronisation precision improved to +/-555ns on
an IMX6DL with an MV88E6220 switch attached.

This patchset takes into account the comments from the following discussions:
- https://lkml.org/lkml/2019/8/2/1364
- https://lkml.org/lkml/2019/8/5/169

Patch 01 adds the required infrastructure in the MDIO layer.
Patch 02 adds additional PTP offset compensation.
Patch 03 adds support for the PTP_SYS_OFFSET_EXTENDED ioctl in the mv88e6xxx driver.
Patch 04 adds support for the PTP system timestamping in the imx-fec driver.

The following tests show the improvement caused by each patch. The system clock
precision was set to 15ns instead of 333ns (as described in https://lkml.org/lkml/2019/8/2/1364).

Without this patchset applied, the phc2sys synchronisation performance was very
poor:

offset: min -27120 max 28840 mean 2.44 stddev 8040.78 count 1236
delay: min 282103 max 386385 mean 352568.03 stddev 27814.27 count 1236
(test runtime 20 minutes)

Results after appling patch 01-03:

offset: min -12316 max 13314 mean -9.38 stddev 4274.82 count 1022
delay: min 69977 max 96266 mean 87939.04 stddev 6466.17 count 1022
(test runtime 16 minutes)

Results after appling patch 04:

offset: min -788 max 528 mean -0.06 stddev 185.02 count 7171
delay: min 1773 max 2031 mean 1909.43 stddev 33.74 count 7171
(test runtime 119 minutes)

Hubert Feurstein (4):
net: mdio: add support for passing a PTP system timestamp to the
mii_bus driver
net: mdio: add PTP offset compensation to mdiobus_write_sts
net: dsa: mv88e6xxx: extend PTP gettime function to read system clock
net: fec: add support for PTP system timestamping for MDIO devices

drivers/net/dsa/mv88e6xxx/chip.h | 2 +
drivers/net/dsa/mv88e6xxx/ptp.c | 11 +--
drivers/net/dsa/mv88e6xxx/smi.c | 7 +-
drivers/net/ethernet/freescale/fec_main.c | 7 +-
drivers/net/phy/mdio_bus.c | 88 +++++++++++++++++++++++
include/linux/mdio.h | 5 ++
include/linux/phy.h | 42 +++++++++++
7 files changed, 156 insertions(+), 6 deletions(-)

--
2.22.1

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