Device Tree Compilation warning on interrupts_property

JohnKlug — Thu, 24 Aug 2023 21:20:51 GMT

I am using the i.MX6ULL with the PCA953X driver.

My 1st question is how do I pick an interrupt? I picked 31 (decimal) because it does not occur elsewhere in device tree.

My 2nd question is on the cause of a warning.

When I try to compile my tree I get a warning:

/home/jklug/mlinux-iotr/build/tmp/work-shared/iotr/kernel-source/arch/arm/boot/dts/imx6ul.dtsi:547.5-28: Warning (interrupts_property): /soc/aips-bus@2100000/i2c@21a8000/pca9538@71:#interrupt-cells: size is (12), expected multiple of 8

Since #interrupt-cells is used frequently without any warnings, I am assuming something is wrong with my device tree.

Here is a segment of the input. I am using the i.MX6ULL processor:

gpio6:pca9538@71 { // GPIO Expander pinctrl-0 = <&pinctrl_gpio6_int>; compatible = "nxp,pca9538"; reg = <0x71>; gpio-controller; #gpio-cells = <2>; vcc-supply = <&dummy_reg_33>; // Driver wants a regulator? #interrupt-cells = <2>; interrupt-parent = <&gpio3>; interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_LOW>; gpio-line-names = "g6_0", "g6_1", "RS232_RS485_UART3_EN", "RS232_UART2_EN", "RS485_TERM_EN", "g6_5", "USER_DIO_IN", "USER_DIO_OUT"; };

I derived this from examples here:
PCA9555

and here:
PCA9538

Re: Device Tree Compilation warning on interrupts_property

JohnKlug — Fri, 25 Aug 2023 15:34:50 GMT

I think I now understand this. interrupt-cells is the number of 32 bit words that is used to describe a single interrupt specified by the "interrupts" property in children.

Some interrupt parents require 3 parameters, and some require 2 from the imx6ul.dtsi portion of device tree.

Example:

gpc: gpc@20dc000 { compatible = "fsl,imx6ul-gpc", "fsl,imx6q-gpc"; reg = <0x020dc000 0x4000>; interrupt-controller; #interrupt-cells = <3>; interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>; interrupt-parent = <&intc>; fsl,mf-mix-wakeup-irq = <0x7c00000 0x7d00 0x0 0x1400640>; };

When this interrupt controller is used, we need 3 parameters to the interrupt:

tempmon: tempmon { compatible = "fsl,imx6ul-tempmon", "fsl,imx6sx-tempmon"; interrupt-parent = <&gpc>; interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>; fsl,tempmon = <&anatop>; nvmem-cells = <&tempmon_calib>, <&tempmon_temp_grade>; nvmem-cell-names = "calib", "temp_grade"; clocks = <&clks IMX6UL_CLK_PLL3_USB_OTG>; };

So because the gic controller requires 3 parameters in the interrupts property, three thirty-two bit words are specified.

In my case, the parent is the GPIO controller built into the i.MX6:

gpio3: gpio@20a4000 { compatible = "fsl,imx6ul-gpio", "fsl,imx35-gpio"; reg = <0x020a4000 0x4000>; interrupts = <GIC_SPI 70 IRQ_TYPE_LEVEL_HIGH>, <GIC_SPI 71 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clks IMX6UL_CLK_GPIO3>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; gpio-ranges = <&iomuxc 0 65 29>; };

It specified gpio-cells of 2, so my gpio6 interrupt controller, which has a parent interrupt controller of gpio3 must only use 2 words per "interrupts" interrupt.

i.MX ProcessorsのトピックDevice Tree Compilation warning on interrupts_property

Device Tree Compilation warning on interrupts_property

Re: Device Tree Compilation warning on interrupts_property