ARM: dts: omap4-droid4: Fix spi configuration and increase rate

We can currently sometimes get "RXS timed out" errors and "EOT timed out"
errors with spi transfers.

These errors can be made easy to reproduce by reading the cpcap iio
values in a loop while keeping the CPUs busy by also reading /dev/urandom.

The "RXS timed out" errors we can fix by adding spi-cpol and spi-cpha
in addition to the spi-cs-high property we already have.

The "EOT timed out" errors we can fix by increasing the spi clock rate
to 9.6 MHz. Looks similar MC13783 PMIC says it works at spi clock rates
up to 20 MHz, so let's assume we can pick any rate up to 20 MHz also
for cpcap.

Cc: [email protected]
Cc: Merlijn Wajer <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: Sebastian Reichel <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/arm/boot/dts/motorola-cpcap-mapphone.dtsi b/arch/arm/boot/dts/motorola-cpcap-mapphone.dtsi
index e39eee628afd..08a7d3ce383f 100644
--- a/arch/arm/boot/dts/motorola-cpcap-mapphone.dtsi
+++ b/arch/arm/boot/dts/motorola-cpcap-mapphone.dtsi
@@ -13,8 +13,10 @@
 		#interrupt-cells = <2>;
 		#address-cells = <1>;
 		#size-cells = <0>;
-		spi-max-frequency = <3000000>;
+		spi-max-frequency = <9600000>;
 		spi-cs-high;
+		spi-cpol;
+		spi-cpha;
 
 		cpcap_adc: adc {
 			compatible = "motorola,mapphone-cpcap-adc";