I have written an RTDM SPI driver for the imx6 chip. It follows the
broadcom SPI driver except where the chips differ. I am using xenomai 3.0.5.

In testing, the driver works 100% of the time. When we are using it with
out app we intermittently read zeros in the read-time application after
after calling the transfer_iobufs.

I used a SPI sniffer to verify that the 4 words (16 bit words) are correct
(not zero). I was also able to verify that the driver copied the values out
of the RX hardware buffer into the shared mmap.

On the app side, this works fine 99% of the time. Every once in a while one
or more of the values will be zero. It is not consistent which value(s) are
zero.

I was wondering if there is some sort of latency with the shared mmap, I
have attached a test program I wrote. The commands are being sent to an
FPGA which responds. The application is doing a lot of SPI transactions.

I've attached the test program and the driver for anyone interested.

Thanks,

Jackson Jones
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