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SPI read problem on iMX6.UL (no MISO data)

Question asked by colinhelliwell on Aug 25, 2018
Latest reply on Aug 26, 2018 by igorpadykov

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.

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