Devices with dynamic frequency scaling adjust the frequency as needed. For
those we only care about the maximum frequency, not the various in betweens.
https://bugs.freedesktop.org/show_bug.cgi?id=87435#c8
# MOUSE_DPI=<dpi>[@<frequency>]
#
# Where <dpi> is the resolution in dots per inch, and <frequency> the
# MOUSE_DPI=<dpi>[@<frequency>]
#
# Where <dpi> is the resolution in dots per inch, and <frequency> the
-# optional sampling frequency in Hz.
+# sampling frequency in Hz (optional). If a device supports dynamic
+# frequency scaling, the maximum frequency should be used. For devices
+# supporting multiple fixed frequencies, see below.
#
# The value of MOUSE_DPI is:
# - a single integer for single-resolution mice, e.g.
#
# The value of MOUSE_DPI is:
# - a single integer for single-resolution mice, e.g.
# ascending order, whichever appropriate.
#
# The frequency must be given to either none or all resolutions. If the
# ascending order, whichever appropriate.
#
# The frequency must be given to either none or all resolutions. If the
-# device supports multiple frequencies, the order of items is
+# device supports multiple fixed frequencies, the order of items is
# MOUSE_DPI=r1@f1 r2@f1 r3@f1 r1@f2 r2@f2 r3@f2
#
# If the default manufacturer-set resolution is unclear, a resolution of
# MOUSE_DPI=r1@f1 r2@f1 r3@f1 r1@f2 r2@f2 r3@f2
#
# If the default manufacturer-set resolution is unclear, a resolution of