Input: matrix_keypad - add option to drive inactive columns

The gpio-matrix-keypad driver normally sets inactive columns as inputs
while scanning. This does not work for all hardware, which may require
the inactive columns to be actively driven in order to overcome any
pull-ups/downs on the columns.

Signed-off-by: David Rivshin <drivshin@allworx.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt b/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt
index d0ea09ba249f..570dc10f0cd7 100644
--- a/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt
+++ b/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt
@@ -24,6 +24,8 @@ Optional Properties:
 - debounce-delay-ms:    debounce interval in milliseconds
 - col-scan-delay-us:    delay, measured in microseconds, that is needed
                         before we can scan keypad after activating column gpio
+- drive-inactive-cols:  drive inactive columns during scan,
+                        default is to turn inactive columns into inputs.
 
 Example:
         matrix-keypad {