diff options
| author | Daniel Machon <daniel.machon@microchip.com> | 2026-02-12 14:02:30 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-02-13 23:25:49 +0300 |
| commit | a49d2a2c37a6252c41cbdd505f9d1c58d5a3817a (patch) | |
| tree | 51b4447418d3a92d822aee76e0446cc3e6a33d47 | |
| parent | 8244f959e2c125c849e569f5b23ed49804cce695 (diff) | |
| download | linux-a49d2a2c37a6252c41cbdd505f9d1c58d5a3817a.tar.xz | |
net: sparx5/lan969x: fix PTP clock max_adj value
The max_adj field in ptp_clock_info tells userspace how much the PHC
clock frequency can be adjusted. ptp4l reads this and will never request
a correction larger than max_adj.
On both sparx5 and lan969x the clock offset may never converge because
the servo needs a frequency correction larger than the current max_adj
of 200000 (200 ppm) allows. The servo rails at the max and the offset
stays in the tens of microseconds.
The hardware has no inherent max adjustment limit; frequency correction
is done by writing a 64-bit clock period increment to CLK_PER_CFG, and
the register has plenty of range. The 200000 value was just an overly
conservative software limit. The max_adj is shared between sparx5 and
lan969x, and the increased value is safe for both.
Fix this by increasing max_adj to 10000000 (10000 ppm), giving the
servo sufficient headroom.
Fixes: 0933bd04047c ("net: sparx5: Add support for ptp clocks")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260212-sparx5-ptp-max-adj-v2-v1-1-06b200e50ce3@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c b/drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c index 2f168700f63c..8b2e07821a95 100644 --- a/drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c +++ b/drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c @@ -576,7 +576,7 @@ static int sparx5_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta) static struct ptp_clock_info sparx5_ptp_clock_info = { .owner = THIS_MODULE, .name = "sparx5 ptp", - .max_adj = 200000, + .max_adj = 10000000, .gettime64 = sparx5_ptp_gettime64, .settime64 = sparx5_ptp_settime64, .adjtime = sparx5_ptp_adjtime, |