Debian 9 / Kernel 4.19 - Spi writes doesn't work

I’m using image and source for the kernel from 4.19.5 kernel based Debian snapshot image release for HiKey960.
With a few patches on top to get I2S0 working, but I SPI2 doesn’t work. Only half of spi writes go through.

I enabled a few traces:

echo 1 > /sys/kernel/debug/tracing/events/regmap/regmap_hw_write_start/enable
echo 1 > /sys/kernel/debug/tracing/events/regmap/regmap_hw_write_done/enable
echo 1 > /sys/kernel/debug/tracing/events/regmap/regmap_async_write_start/enable

But I can see that any regmap_async_write_start is not in the BUS using my logic saleae.
There is also this bug about SPI on HIKEY960 :

It also seems that john.stultz is working on a main line version of Hikey, but the DTS for hikey960 on this branch doesn’t have DMA too.



Debugging printk/pr_info doesn’t work because this is a timing issue, to many prints makes everything work.

A mdelay(30) on the begging of _regmap_raw_write_impl makes SPI2 work.