Input: ads7846: Add description how to use internal reference (ADS7846)

By simply setting vref-mv to 0 the internal reference will be used.
Document that!

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/input/ads7846.txt b/Documentation/devicetree/bindings/input/ads7846.txt
index 33a1638b61d6..c6cfe2e3ed41 100644
--- a/Documentation/devicetree/bindings/input/ads7846.txt
+++ b/Documentation/devicetree/bindings/input/ads7846.txt
@@ -29,6 +29,8 @@ Optional properties:
         ti,vref-delay-usecs             vref supply delay in usecs, 0 for
                                         external vref (u16).
         ti,vref-mv                      The VREF voltage, in millivolts (u16).
+                                        Set to 0 to use internal refernce
+                                        (ADS7846).
         ti,keep-vref-on                 set to keep vref on for differential
                                         measurements as well
         ti,swap-xy                      swap x and y axis