How to unhog pin in the device tree

I am trying to configure the device tree to enable uart3 on the colibri imx6ull. I changed the default provided device tree file (imx6ull-colibri-wifi-eval-v3.dts) to the following:

/dts-v1/;
#include "imx6ull.dtsi"
#include "imx6ull-colibri.dtsi"
#include "imx6ull-colibri-wifi.dtsi"
#include "imx6ull-colibri-eval-v3.dtsi"

/ {
	model = "Toradex Colibri iMX6ULL 512MB Custom";
	compatible = "toradex,colibri_imx6ull-wifi-eval", "fsl,imx6ull";
};
&iomuxc {
	imx6ull-custom {
		pinctrl_uart3: uart3-grp {
			fsl,pins = <
				MX6UL_PAD_UART3_TX_DATA__UART3_DTE_RX	0x1b0b1
				MX6UL_PAD_UART3_RX_DATA__UART3_DTE_TX	0x1b0b1
			>;
		};
	};
};

&uart3 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart3>;
	fsl,dte-mode;
	status = "okay";
};

The problem is it does not work unless I also remove the corresponding pins from the pin hog group in the imx6ull-colibri.dtsi file:

pinctrl_hog_1: hoggrp-1 {
			fsl,pins = <
				MX6UL_PAD_ENET1_RX_DATA0__GPIO2_IO00	0x74 /* SODIMM 55 */
				MX6UL_PAD_ENET1_RX_DATA1__GPIO2_IO01	0x74 /* SODIMM 63 */
				/*MX6UL_PAD_UART3_RX_DATA__GPIO1_IO25	0X14  SODIMM 77 */
				MX6UL_PAD_JTAG_TCK__GPIO1_IO14		0x14 /* SODIMM 99 */
				MX6UL_PAD_NAND_CE1_B__GPIO4_IO14	0x14 /* SODIMM 133 */
				/*MX6UL_PAD_UART3_TX_DATA__GPIO1_IO24	0x14  SODIMM 135 */
				MX6UL_PAD_UART3_CTS_B__GPIO1_IO26	0x14 /* SODIMM 100 */
				MX6UL_PAD_JTAG_TRST_B__GPIO1_IO15	0x14 /* SODIMM 102 */
				MX6UL_PAD_ENET1_RX_ER__GPIO2_IO07	0x14 /* SODIMM 104 */
				MX6UL_PAD_UART3_RTS_B__GPIO1_IO27	0x14 /* SODIMM 186 */
			>;
		};

When I comment out the pins it works, however this doesn’t seem like the cleanest way of modifying the device tree. Is there a way I can get it working without having to edit the .dtsi files?

Thanks

Unfortunately there is no way to delete/mask single pins within a pingroup.

However, you can overwrite properties. In your case you would need to add &iomuxc and set pinctrl-0 = to all but pinctrl_hog_1. Then create a new pinctrl_hog_1 without the two pins , and add it as well.

See also Device Tree Customization.