ARM: dts: imx27-eukrea: Remove invalid spi-cpol

The ADS7846 timing diagrams show DCLK low when inactive, and its pin descriptions specify that DIN is latched on the rising edge of DCLK while DOUT is shifted on the falling edge. This corresponds to SPI mode 0, with CPOL=0 and CPHA=0.

The spi-cpol property without spi-cpha instead selects SPI mode 2, which uses the opposite clock edges and does not match the ADS7846 serial interface. Remove the invalid property.

This also matches the driver behavior: ads7846_probe() clears SPI_MODE_X_MASK and selects SPI_MODE_0 before calling spi_setup().

This fixes the following dtbs_check warning:

imx27-eukrea-mbimxsd27-baseboard.dtb: ads7846@0 (ti,ads7846):
Unevaluated properties are not allowed (spi-cpol was unexpected)

---
Changes since v1:

- Remove spi-cpol from the dts instead of adding it to the binding. (Sashiko)

 arch/arm/boot/dts/nxp/imx/imx27-eukrea-mbimxsd27-baseboard.dts | 1 -
 1 file changed, 1 deletion(-)

index 26833ed3339e..cf5603ec6826 100644
@@ -77,7 +77,6 @@ ads7846@0 {
 		pinctrl-0 = <&pinctrl_touch>;
 		reg = <0>;
 		interrupts-extended = <&gpio4 25 IRQ_TYPE_LEVEL_LOW>;
-		spi-cpol;
 		spi-max-frequency = <1500000>;
 		ti,keep-vref-on;
 	};

2.43.0

From: Frank Li <[email protected]>

Applied to imx/dt-intend (will appear to linux-next after v7.4-rc1), thanks!

[1/1] ARM: dts: imx27-eukrea: Remove invalid spi-cpol

      commit: d8c85b09c98585528c6647a5e8e52d053adddcef

Best regards,
--
Frank Li <[email protected]>