I'm using the IMX6UL in a new board we've built. This board uses ecspi1-4.
On ecspi1 and ecspi2, I have pull-ups on CS and pull-downs on CLK and MOSI and have no problem talking to the devices connected there.
On ecspi3 and ecspi4, I do not have pull-ups or pull-downs and talk to a different type of devices (the reason why is b/c I didn't review the schematic and catch this until very recently).
Anyway, I cannot talk to my SPI device on on ecspi3 or ecspi4. I believe this is due to the lack of pull-up/down, but I'm not sure. I will bread-board this change ASAP, but wanted to ask here if the pull-up/down resistors are necessary, or if there's a GPIO/SPI controller setting on the IMX6UL that can accomodate this.
Thanks in advance for any suggestions.