Index: head/usr.sbin/pwm/pwm.8
===================================================================
--- head/usr.sbin/pwm/pwm.8	(revision 349144)
+++ head/usr.sbin/pwm/pwm.8	(revision 349145)
@@ -1,115 +1,118 @@
 .\" Copyright (c) 2018 Emmanuel Vadot <manu@freebsd.org>
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
 .\" are met:
 .\" 1. Redistributions of source code must retain the above copyright
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 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
 .\"
 .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
 .\" $FreeBSD$
 .\"
 .Dd June 17, 2019
 .Dt PWM 8
 .Os
 .Sh NAME
 .Nm pwm
 .Nd configure pwm controller
 .Sh SYNOPSIS
 .Nm
 .Op Fl f Ar device
 .Fl c Ar channel
 .Fl E
 .Nm
 .Op Fl f Ar device
 .Fl c Ar channel
 .Fl D
 .Nm
 .Op Fl f Ar device
 .Fl c Ar channel
 .Fl C
 .Nm
 .Op Fl f Ar device
 .Fl c Ar channel
 .Fl p Ar period
 .Nm
 .Op Fl f Ar device
 .Fl c Ar channel
 .Fl d Ar duty
 .Sh DESCRIPTION
 The
 .Nm
 utility can be used to configure pwm controllers.
 .Pp
 The options are as follow:
 .Bl -tag -width "-c channel"
 .It Fl c Ar channel
-Channel number to operate on
+Channel number to operate on.
 .It Fl f Ar device
 Device to operate on.
 If not specified,
 .Pa /dev/pwm/pwmc0.0
 is used.
 If an unqualified name is provided,
 .Pa /dev/pwm
 is automatically prepended.
 .It Fl E
-Enable the pwm channel
+Enable the pwm channel.
 .It Fl D
-Disable the pwm channel
+Disable the pwm channel.
 .It Fl C
-Show the configuration of the pwm channel
+Show the configuration of the pwm channel.
 .It Fl p Ar period
 Configure the period (in nanoseconds) of the pwm channel
 .It Fl d Ar duty
-Configure the duty (in nanoseconds or percentage) of the pwm channel
+Configure the duty (in nanoseconds or percentage) of the pwm channel.
+Duty is the portion of the
+.Ar period
+during which the signal is asserted.
 .El
 .Sh EXAMPLES
 .Bl -bullet
 .It
 Show the configuration of the pwm channel:
 .Bd -literal
 pwm -f /dev/pwm/pwmc0.1 -C
 .Ed
 .It
 Configure a 50000 ns period and a 25000 ns duty cycle:
 .Bd -literal
 pwm -f pwmc1.1 -p 50000 -d 25000
 .Ed
 .It
 Configure a 50% duty cycle on the device and channel which
 were configured in
 .Xr pwmc 4
 to have the label
 .Pa backlight :
 .Bd -literal
 pwm -f backlight -d 50%
 .Ed
 .El
 .Sh SEE ALSO
 .Xr pwm 9 ,
 .Xr pwmbus 9
 .Sh HISTORY
 The
 .Nm
 utility appeared in
 .Fx 13.0 .
 .Sh AUTHORS
 .An -nosplit
 The
 .Nm
 utility and this manual page were written by
 .An Emmanuel Vadot Aq Mt manu@FreeBSD.org .