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From:   Marcel Ziswiler <marcel@ziswiler.com>
To:     linux-arm-kernel@lists.infradead.org
Cc:     Philippe Schenker <philippe.schenker@toradex.com>,
        Denys Drozdov <denys.drozdov@toradex.com>,
        Marcel Ziswiler <marcel.ziswiler@toradex.com>,
        Fabio Estevam <festevam@gmail.com>,
        Frank Rowand <frowand.list@gmail.com>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1 01/14] ARM: dts: imx6ull-colibri: use pull-down for adc pins
Date:   Thu, 14 Apr 2022 10:50:53 +0200
Message-Id: <20220414085106.18621-2-marcel@ziswiler.com>
In-Reply-To: <20220414085106.18621-1-marcel@ziswiler.com>
References: <20220414085106.18621-1-marcel@ziswiler.com>
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From: Philippe Schenker <philippe.schenker@toradex.com>

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>
---

 arch/arm/boot/dts/imx6ull-colibri.dtsi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/boot/dts/imx6ull-colibri.dtsi b/arch/arm/boot/dts/imx6ull-colibri.dtsi
index 7f35a06dff95..84bb7574d211 100644
--- a/arch/arm/boot/dts/imx6ull-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6ull-colibri.dtsi
@@ -52,6 +52,8 @@ reg_sd1_vmmc: regulator-sd1-vmmc {
 &adc1 {
 	num-channels = <10>;
 	vref-supply = <&reg_module_3v3_avdd>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_adc1>;
 };
 
 &can1 {
@@ -214,6 +216,16 @@ &wdog1 {
 };
 
 &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 */
-- 
2.35.1