On Tue, Nov 19, 2019 at 10:28:15AM +0100, Marc Gonzalez wrote: > Hello, > > The board I'm working on provides a TCA9539 I/O expander. > Or, as the datasheet(*) calls it, a "Low Voltage 16-Bit I2C and > SMBus Low-Power I/O Expander with Interrupt Output, Reset Pin, > and Configuration Registers" > > (*) http://www.ti.com/lit/ds/symlink/tca9539.pdf > > The binding is documented in Documentation/devicetree/bindings/gpio/gpio-pca953x.txt > > I have some doubts about the interrupt output, described as: > > Optional properties: > - interrupts: interrupt specifier for the device's interrupt output. > > In my board's DT, the I/O expander is described as: > > exp1: gpio@74 { > compatible = "ti,tca9539"; > reg = <0x74>; > gpio-controller; > #gpio-cells = <2>; > reset-gpios = <&tlmm 96 GPIO_ACTIVE_LOW>; > pinctrl-names = "default"; > pinctrl-0 = <&top_exp_rst>; > interrupt-parent = <&tlmm>; > interrupts = <42 IRQ_TYPE_LEVEL_HIGH>; This specifies an interrupt signal, number 42, on the tlmm interrupt controller. It isn't a GPIO specification. Not every interrupt is a GPIO, and some SoCs can have dedicated interrupt pins that are exactly that. Hence, needlessly limiting an external device to requiring a GPIO for its interrupt is detrimental. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
