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| author | Hans Verkuil <hverkuil@xs4all.nl> | 2017-12-16 11:44:13 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2018-01-23 14:05:00 +0100 |
| commit | dac15ed62dc9d7898d3695a3c393d6f712d66185 (patch) | |
| tree | 94974021d2fdbc305d8f8aacb80e052e1fbe5802 /Documentation | |
| parent | media: dw9714: annotate a __be16 integer value (diff) | |
| download | linux-dac15ed62dc9d7898d3695a3c393d6f712d66185.tar.xz linux-dac15ed62dc9d7898d3695a3c393d6f712d66185.zip | |
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: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: <stable@vger.kernel.org> # for v4.15
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/media/cec-gpio.txt | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/media/cec-gpio.txt b/Documentation/devicetree/bindings/media/cec-gpio.txt index 46a0bac8b3b9..12fcd55ed153 100644 --- a/Documentation/devicetree/bindings/media/cec-gpio.txt +++ b/Documentation/devicetree/bindings/media/cec-gpio.txt @@ -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> |