commit 6953c57ab172 "gpio: of: Handle SPI chipselect legacy bindings" did introduce logic to centrally handle the legacy spi-cs-high property in combination with cs-gpios. This assumes that the polarity of the CS has to be inverted if spi-cs-high is missing, even and especially if non-legacy GPIO_ACTIVE_HIGH is specified. The DTS for the GTA04 was orginally introduced under the assumption that there is no need for spi-cs-high if the gpio is defined with proper polarity GPIO_ACTIVE_HIGH. This was not a problem until gpiolib changed the interpretation of GPIO_ACTIVE_HIGH and missing spi-cs-high. The effect is that the missing spi-cs-high is now interpreted as CS being low (despite GPIO_ACTIVE_HIGH) which turns off the SPI interface when the panel is to be programmed by the panel driver. Therefore, we have to add the redundant and legacy spi-cs-high property to properly pass through the legacy handler. Since this is nowhere documented in the bindings, we add some words of WARNING. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> --- Documentation/devicetree/bindings/spi/spi-bus.txt | 6 ++++++ arch/arm/boot/dts/omap3-gta04.dtsi | 1 + 2 files changed, 7 insertions(+) diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 1f6e86f787ef..982aa590058b 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -47,6 +47,10 @@ cs1 : native cs2 : &gpio1 1 0 cs3 : &gpio1 2 0 +WARNING: the polarity of cs-gpios may be inverted in some cases compared +to what is specified in the third parameter. In that case the spi-cs-high +property must be defined for slave nodes. + SPI slave nodes must be children of the SPI controller node. @@ -69,6 +73,8 @@ All slave nodes can contain the following optional properties: phase (CPHA) mode. - spi-cs-high - Empty property indicating device requires chip select active high. + WARNING: this is especially required even if the cs-gpios + define the gpio as GPIO_ACTIVE_HIGH - spi-3wire - Empty property indicating device requires 3-wire mode. - spi-lsb-first - Empty property indicating device requires LSB first mode. - spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI. diff --git a/arch/arm/boot/dts/omap3-gta04.dtsi b/arch/arm/boot/dts/omap3-gta04.dtsi index 9a9a29fe88ec..47bab8e1040e 100644 --- a/arch/arm/boot/dts/omap3-gta04.dtsi +++ b/arch/arm/boot/dts/omap3-gta04.dtsi @@ -124,6 +124,7 @@ spi-max-frequency = <100000>; spi-cpol; spi-cpha; + spi-cs-high; backlight= <&backlight>; label = "lcd"; -- 2.19.1
