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| author |   Kurt Kanzenbach <kurt@linutronix.de> | 2021-11-22 12:19:31 +0100 |
|---|---|---|
| committer |   Jakub Kicinski <kuba@kernel.org> | 2021-11-23 20:11:05 -0800 |
| commit | c6d5f1933085f9a92ed5c256a859ab31c7a35f88 (patch) | |
| tree | 652bed7110baf5cc643b18ddd9194180453423bd /net | |
| parent | net: remove .ndo_change_proto_down (diff) | |
| download | linux-dev-c6d5f1933085f9a92ed5c256a859ab31c7a35f88.tar.xz linux-dev-c6d5f1933085f9a92ed5c256a859ab31c7a35f88.zip | |
net: stmmac: Calculate CDC error only once
The clock domain crossing error (CDC) is calculated at every fetch of Tx or Rx
timestamps. It includes a division. Especially on arm32 based systems it is
expensive. It also requires two conditionals in the hotpath.
Add a compensation value cache to struct plat_stmmacenet_data and subtract it
unconditionally in the RX/TX functions which spares the conditionals.
The value is initialized to 0 and if supported calculated in the PTP
initialization code.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20211122111931.135135-1-kurt@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
0 files changed, 0 insertions, 0 deletions