ARM: dts: imx6ull-colibri: use pull-down for adc pins

Disable the keeper and enable a 100k pull-down on the ADC pins as per
the following note in section 13.2 of the i.MX 6ULL Application
Processor Reference Manual, Rev. 1, 11/2017 [1]:

The keeper causes an undesired jump behavior in ADC. To avoid the
problem, disable keeper before starting ADC.

[1] https://www.nxp.com/webapp/Download?colCode=IMX6ULLRM

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Signed-off-by: Denys Drozdov <denys.drozdov@toradex.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

diff --git a/arch/arm/boot/dts/imx6ull-colibri.dtsi b/arch/arm/boot/dts/imx6ull-colibri.dtsi
index 7f35a06..84bb757 100644 (file)
--- a/arch/arm/boot/dts/imx6ull-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6ull-colibri.dtsi
@@ -52,6 +52,8 @@
 &adc1 {
        num-channels = <10>;
        vref-supply = <&reg_module_3v3_avdd>;
+       pinctrl-names = "default";
+       pinctrl-0 = <&pinctrl_adc1>;
 };
 
 &can1 {
@@ -214,6 +216,16 @@
 };
 
 &iomuxc {
+
+       pinctrl_adc1: adc1grp {
+               fsl,pins = <
+                       MX6UL_PAD_GPIO1_IO00__GPIO1_IO00        0x3000 /* SODIMM 8 */
+                       MX6UL_PAD_GPIO1_IO01__GPIO1_IO01        0x3000 /* SODIMM 6 */
+                       MX6UL_PAD_GPIO1_IO08__GPIO1_IO08        0x3000 /* SODIMM 4 */
+                       MX6UL_PAD_GPIO1_IO09__GPIO1_IO09        0x3000 /* SODIMM 2 */
+               >;
+       };
+
        pinctrl_can_int: canint-grp {
                fsl,pins = <
                        MX6UL_PAD_ENET1_TX_DATA1__GPIO2_IO04    0x13010 /* SODIMM 73 */