Hi. We are building a i.MX6ULL system with a modem connected to CPU serial port, but the DCD signal is routed via an IO expander (PCA953x). This is configured via devicetree:
&uart2 {
...
dcd-gpios = <&i2c_gpio1 6 GPIO_ACTIVE_LOW>;
};
However, when booting we get:
imx-uart 21e8000.serial: failed to request irq for dcd (idx=0, err=-22)
Don't really know how this can be fixed. However, perhaps it would be easier to use a polling solution for DCD instead? imx.c actually polls for it's own DCD, but a naive implementation to poll the IO expander does not work; only gives "BUG: scheduling while atomic".
So, how is this supposed to work...? imx.c and serial_mctrl_gpio.c obviously tries to support generic GPIO via gpiod, but for some reason this does not work for our IO expander. Thankful for any help.
Using i.MX yocto platform L5.4.24_2.1.0. Also tried kernel from lf-5.10.y.
