This article is a collection of examples of Device Tree customization. Examples may get obsolete over time, please check the testing environment details and make similar changes for the device and version you are using.
Tested on Embedded Linux BSP 3.0b3 (toradex_4.14-2.0.x-imx) / Apalis iMX8X / Apalis Evaluation Board
Note: Please note that the following device trees do not apply for Apalis iMX8QP or Apalis iMX8QM. In those cases, you should make similar changes but in the corresponding fsl-imx8qm-apalis-v1.1.dtsi and fsl-imx8qm-apalis-eval.dtsi or fsl-imx8qm-apalis-ixora-v1.1.dtsi device trees.
In this documentation, we will change a default unneeded function from its original definition to GPIO.
Basically, the steps are:
In this particular example, we will be changing the SPI0 pins to a sysfs accessed GPIO.
arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis-eval.dtsidiff --git a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis-eval.dtsi b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis-eval.dtsi index c957472c3652..12652f69f5ff 100644 --- a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis-eval.dtsi +++ b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis-eval.dtsi @@ -199,7 +199,7 @@ /* Apalis SPI1 */ &lpspi0 { - status = "okay"; + status = "disabled"; spidev0: spi@0 { compatible = "toradex,evalspi";
arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis.dtsidiff --git a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis.dtsi b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis.dtsi index 56012aab1cf3..a0292e37af14 100644 --- a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis.dtsi +++ b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-apalis.dtsi @@ -317,7 +317,7 @@ <&pinctrl_gpio8>, <&pinctrl_qspi0a_gpios>, <&pinctrl_sata1_act>, <&pinctrl_reset_moci>, <&pinctrl_mmc1_gpios>, <&pinctrl_dap1_gpios>, - <&pinctrl_parallel_csi>; + <&pinctrl_parallel_csi>, <&pinctrl_gpiospi0>; apalis-imx8qxp { /* Apalis AN1_ADC */ @@ -613,6 +613,17 @@ >; }; + /* Apalis SPI1 pins changed to GPIO*/ + pinctrl_gpiospi0: lpspi0gpiogrp { + fsl,pins = < + SC_P_SPI0_CS0_LSIO_GPIO1_IO08 0x21 /* MXM3 227 */ + SC_P_SPI0_SDI_LSIO_GPIO1_IO05 0x21 /* MXM3 223 */ + SC_P_SPI0_SDO_LSIO_GPIO1_IO06 0x21 /* MXM3 225 */ + SC_P_CSI_EN_LSIO_GPIO3_IO02 0x21 /* MXM3 221 */ + >; + }; + + /* Apalis SPI2 */ pinctrl_lpspi2: lpspi2grp { fsl,pins = <
Note: Pinmux definition are under include/dt-bindings/pinctrl/pads-imx8qpx.h Note: Remember to check the following article to understand the equivalence between physical pins and Linux GPIO: GPIO Alphanumeric to GPIO Numeric Assignment
Tested on Embedded Linux BSP 2.8 / Colibri iMX7 / Colibri Evaluation Board
Remarks: you must check if the SION Bit is available for both the i.MX family you target (i.MX 6, i.MX7, etc,) as well as the specific pin you want to use (SoC pin exposed in the edge connector).
arch/arm/boot/dts/imx7-colibri.dtsidiff --git a/arch/arm/boot/dts/imx7-colibri.dtsi b/arch/arm/boot/dts/imx7-colibri.dtsi index 4a1ef3f83faf..d2449ec2cb22 100644 --- a/arch/arm/boot/dts/imx7-colibri.dtsi +++ b/arch/arm/boot/dts/imx7-colibri.dtsi @@ -365,7 +365,7 @@ pinctrl_gpio1: gpio1-grp { fsl,pins = < - MX7D_PAD_SAI1_RX_SYNC__GPIO6_IO16 0x14 /* SODIMM 77 */ + MX7D_PAD_SAI1_RX_SYNC__GPIO6_IO16 ((1 << 30) | 0x14) /* SODIMM 77 */ MX7D_PAD_EPDC_DATA09__GPIO2_IO9 0x14 /* SODIMM 89 */ MX7D_PAD_EPDC_DATA08__GPIO2_IO8 0x74 /* SODIMM 91 */ MX7D_PAD_LCD_RESET__GPIO3_IO4 0x14 /* SODIMM 93 */
Since Colibri iMX8X doesn't support vidargs customization, any display implementation has to be done at the device tree.
Tested on Embedded Linux BSP 3.0b3 (toradex_4.14-2.0.x-imx) / Colibri iMX8X / Colibri Evaluation Board
Note: This change is compatible with the Toradex Resistive and Capacitive Touch 7" Parallel displays.
You can check the complete documentation of the following parameters at the Kernel Documentation.
arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri.dtsidiff --git a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri.dtsi b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri.dtsi index 8c755fae4f22..eee928b38b49 100644 --- a/arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri.dtsi +++ b/arch/arm64/boot/dts/freescale/fsl-imx8qxp-colibri.dtsi @@ -44,16 +44,17 @@ data-mapping = "bgr666"; panel-timing { - /* Default VESA VGA display timings */ - clock-frequency = <25175000>; - hactive = <640>; - hback-porch = <48>; - hfront-porch = <16>; - hsync-len = <96>; + /* 7.0” WVGA 800 x 3 (RGB) x 480 */ + clock-frequency = <33260000>; + hactive = <800>; vactive = <480>; - vback-porch = <31>; - vfront-porch = <11>; + hback-porch = <216>; + hfront-porch = <40>; + vback-porch = <35>; + vfront-porch = <10>; + hsync-len = <128>; vsync-len = <2>; + pixelclk-active = <0>; };
Tested on Embedded Linux BSP 2.8 / Colibri iMX6ULL / Iris Carrier Board
Remarks: address 68 cannot be used since it is also used by the Iris RTC. The pin AD0 of MPU-6050 has to be driven high.
arch/arm/boot/dts/imx6ull-colibri-eval-v3.dtsidiff --git a/arch/arm/boot/dts/imx6ull-colibri-eval-v3.dtsi b/arch/arm/boot/dts/imx6ull-colibri-eval-v3.dtsi index 5870638c3a6f..c2eb33edae6b 100644 --- a/arch/arm/boot/dts/imx6ull-colibri-eval-v3.dtsi +++ b/arch/arm/boot/dts/imx6ull-colibri-eval-v3.dtsi @@ -166,6 +166,12 @@ compatible = "st,m41t0"; reg = <0x68>; }; + + mpu6050@69 { + compatible = "invensense,mpu6050"; + reg = <0x69>; + status = "okay"; + }; }; &lcdif {
Tested on Embedded Linux BSP 3.0 / Verdin iMX8M Mini / Verdin Development Board
arch/arm64/boot/dts/freescale/fsl-imx8mm-verdin.dtsidiff --git a/arch/arm64/boot/dts/freescale/fsl-imx8mm-verdin.dtsi b/arch/arm64/boot/dts/freescale/fsl-imx8mm-verdin.dtsi index 270aa603ecd0..7ad85155c18c 100755 --- a/arch/arm64/boot/dts/freescale/fsl-imx8mm-verdin.dtsi +++ b/arch/arm64/boot/dts/freescale/fsl-imx8mm-verdin.dtsi @@ -211,6 +211,13 @@ interrupts = <10 IRQ_TYPE_LEVEL_LOW>; micrel,led-mode = <0>; reg = <7>; + txen-skew-ps = <0>; + txd0-skew-ps = <0>; + txd1-skew-ps = <0>; + txd2-skew-ps = <0>; + txd3-skew-ps = <0>; + txc-skew-ps = <1860>; + rxc-skew-ps = <1200>; }; }; };
This section has tips on how to disable hardware interfaces, through examples.
Investigated on Embedded Linux BSP 5.1.0 (kernel branch toradex_5.4-2.1.x-imx) / Apalis iMX8QM V1.1B / no specific carrier board.
Warning: The instructions from this chapter have not been fully validated. They are meant as tips for you to begin your investigation.
To disable those interfaces, you must disable related nodes for each interface. For example, disable the hdmi and related nodes for the HDMI interface. It requires a bit of trial and error, reading the NXP i.MX8 SoC Reference Manual and the Embedded Linux for i.MX Applications Processors Documentation.
See some nodes that you may try to disable, as examples:
