From a49d2a2c37a6252c41cbdd505f9d1c58d5a3817a Mon Sep 17 00:00:00 2001 From: Daniel Machon Date: Thu, 12 Feb 2026 12:02:30 +0100 Subject: [PATCH] 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 Reviewed-by: Maxime Chevallier Link: https://patch.msgid.link/20260212-sparx5-ptp-max-adj-v2-v1-1-06b200e50ce3@microchip.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/microchip/sparx5/sparx5_ptp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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, -- 2.30.2