On a custom board like a sabresd, a imx6qp drives a spi link with a mipi bridge (and other stuffs i2c, ...).
Previously, i used a 4.1.15 linux version and all worked fine. I update to 4.14.78 (sumo-4.14.78-1.0.0_ga) and obviously, there's a problem with spi. I use the basic dts configuration of imx6qpsabresd.
At boot, our spi driver is correctly launched, so chip select and spi pins are correct. But inside the driver, there's registers accesses to the bridge component and this is not good: the spi link seems to hang. I see nothing on the miso pin when reading and other signals (mosi, clk and cs) never stop. I can also see there's seemingly no conflict with other pins. So, i wonder why...
Is threre something particular to do with this linux release in order to have spi function ?
I realize the sdma could be the root cause. Il the kernel log, i have:
imx-sdma 20ec000.sdma: no iram assigned, using external mem
imx-sdma 20ec000.sdma: Falling back to user helper
So it seems sdma driver in not loaded, and so on, spi can't work.
I've read with 4.14.78, it would seem sdma driver needs to be loaded as module. It is really the case ? And then, how to have spi access during the kernel boot ?
Thanks in advance.