[PATCH v2 2/2] man/man2/adjtimex.2: Add error for clock_adjtime

[Georg Sauthoff <mail@gms.tf>]

The ERANGE error can be verified either via trying to adjust the
frequency of a PHC by a value that is outside of [-X,X],
where X=`cat /sys/class/ptp/ptpX/max_adjustment`,
or via checking the kernel source code:

<https://elixir.bootlin.com/linux/v7.2.2/source/drivers/ptp/ptp_clock.c#L164>

Signed-off-by: Georg Sauthoff <mail@gms.tf>
---
 man/man2/adjtimex.2 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/man/man2/adjtimex.2 b/man/man2/adjtimex.2
index 5b9a0667b..6b6ee98b0 100644
--- a/man/man2/adjtimex.2
+++ b/man/man2/adjtimex.2
@@ -537,6 +537,12 @@ .SH ERRORS
 Under Linux, the
 .B CAP_SYS_TIME
 capability is required.
+.TP
+.B ERANGE
+The frequency offset supplied with
+.BR clock_adjtime ()
+is outside of the range clock clk_id supports.
+See also /sys/class/ptp/ptpX/max_adjustment when adjusting a PTP hardware clock.
 .SH ATTRIBUTES
 For an explanation of the terms used in this section, see
 .BR attributes (7).
-- 
2.55.0