[PATCH v3 1/3] docs/pinctrl: update `pins' description under debugfs

[Dario Binacchi <dariobin@libero.it>]

Optionally the `pins' file created inside the `/sys/kernel/debug/pinctrl'
subdirectory of each pin controller device now allows you to set the
mux register of a pin.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
---

(no changes since v1)

 Documentation/driver-api/pin-control.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/driver-api/pin-control.rst b/Documentation/driver-api/pin-control.rst
index e2474425fb0c..3d8192fa45a3 100644
--- a/Documentation/driver-api/pin-control.rst
+++ b/Documentation/driver-api/pin-control.rst
@@ -1447,6 +1447,9 @@ controller device containing these files:
 
 - ``pins``: prints a line for each pin registered on the pin controller. The
   pinctrl driver may add additional information such as register contents.
+  Optionally writes the mux register for the selected pin.
+  e.g. to write the value 0x73 in the mux register of pin 19:
+  echo 19 0x73 >/sys/kernel/debug/pinctrl/pins
 
 - ``gpio-ranges``: print ranges that map gpio lines to pins on the controller
 
-- 
2.17.1