The current documentation does not clearly explain how to invert the SPI CS signal to make it active-high. This makes it very difficult to understand. This patch adds a simple explanation on how to set the CS line in active-high and adds an example to make it easier for users who need that setup for their SPI peripherals. Link: https://forums.raspberrypi.com/viewtopic.php?t=378222 Signed-off-by: Iker Pedrosa <ikerpedrosam@xxxxxxxxx> --- .../bindings/spi/spi-controller.yaml | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml index 093150c0cb87..960d60e653d9 100644 --- a/Documentation/devicetree/bindings/spi/spi-controller.yaml +++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml @@ -69,6 +69,11 @@ properties: Should be generally avoided and be replaced by spi-cs-high + ACTIVE_HIGH. + The simplest way to obtain an active-high CS signal is to configure the + controller's cs-gpio property with the ACTIVE_HIGH flag and set the + peripheral's spi-cs-high property. See example below for a better + understanding. + fifo-depth: $ref: /schemas/types.yaml#/definitions/uint32 description: @@ -189,3 +194,23 @@ examples: stacked-memories = /bits/ 64 <0x10000000 0x10000000>; }; }; + + - | + #include <dt-bindings/gpio/gpio.h> + + spi@20204000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "brcm,bcm2835-spi"; + reg = <0x7e204000 0x1000>; + interrupts = <2 22>; + clocks = <&clk_spi>; + cs-gpios = <&gpio 8 GPIO_ACTIVE_HIGH>; + + display@0 { + compatible = "sitronix,st7920"; + spi-max-frequency = <600000>; + reg = <0>; + spi-cs-high; + }; + }; -- 2.47.1
