Has anyone had (and ideally solved!) problems with SPI master on the UL?
I’m using a 4.4.40 kernel, and trying a simple loopback test (MOSI shorted to MISO) with the spi_imx driver module and “spidev_test” utility.
I also have a bus analyser hooked up and this sees the data on MISO as well as MOSI, but the utility just gets zeroes back.
My board uses an SOM and I can swap the UL for a iMX6.S and it works – so I know there isn’t a wiring fault on the board. I don't think there's any significant difference in kernel config (though obviously the device trees are quite different).
I feel the device tree is probably correct, because Clk/SS/MOSI are all working; just not MISO. I have my own top-level dts for my board, but it includes the imx6ul-tx6ul.dtsi and imx6ul.dtsi from the kernel source.
Any thoughts please as to where the problem could be? Thanks.