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Commit dac15ed6 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

media: dt-bindings/media/cec-gpio.txt: mention the CEC/HPD max voltages 



Mention the maximum voltages of the CEC and HPD lines. Since in the example
these lines are connected to a Raspberry Pi and the Rpi GPIO lines are 3.3V
it is a good idea to warn against directly connecting the HPD to the Raspberry
Pi's GPIO line.

Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Cc: <stable@vger.kernel.org>      # for v4.15
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent a4a02b6e

Documentation/devicetree/bindings/media/cec-gpio.txt

+5 −1
Original line number Diff line number Diff line
@@ -4,6 +4,10 @@ The HDMI CEC GPIO module supports CEC implementations where the CEC line 
is hooked up to a pull-up GPIO line and - optionally - the HPD line is

hooked up to another GPIO line.



Please note: the maximum voltage for the CEC line is 3.63V, for the HPD

line it is 5.3V. So you may need some sort of level conversion circuitry

when connecting them to a GPIO line.



Required properties:

  - compatible: value must be "cec-gpio".

  - cec-gpios: gpio that the CEC line is connected to. The line should be
@@ -21,7 +25,7 @@ the following property is optional: 


Example for the Raspberry Pi 3 where the CEC line is connected to

pin 26 aka BCM7 aka CE1 on the GPIO pin header and the HPD line is

connected to pin 11 aka BCM17:

connected to pin 11 aka BCM17 (some level shifter is needed for this!):



#include <dt-bindings/gpio/gpio.h>