ptp: ocp: fix start time alignment in ptp_ocp_signal_set

In ptp_ocp_signal_set, the start time for periodic signals is not
aligned to the next period boundary. The current code rounds up the
start time and divides by the period but fails to multiply back by
the period, causing misaligned signal starts. Fix this by multiplying
the rounded-up value by the period to ensure the start time is the
closest next period.

Fixes: 4bd46bb037f8e ("ptp: ocp: Use DIV64_U64_ROUND_UP for rounding.")
Signed-off-by: Sagi Maimon <maimon.sagi@gmail.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20250415053131.129413-1-maimon.sagi@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 7945c6be1f7ce451b382c919d4a9a9ee400d7805..faf6e027f89ab4a5a9c03eac062d1f97711f770b 100644 (file)
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -2067,6 +2067,7 @@ ptp_ocp_signal_set(struct ptp_ocp *bp, int gen, struct ptp_ocp_signal *s)
        if (!s->start) {
                /* roundup() does not work on 32-bit systems */
                s->start = DIV64_U64_ROUND_UP(start_ns, s->period);
+               s->start *= s->period;
                s->start = ktime_add(s->start, s->phase);
        }