I was disabling Audio on my board via menuconfig because I don't have any need for it. Once I disabled "Sound card support" from the Device Drivers menu and checked the resultant .config file I noticed that CONFIG_FIQ was removed as well.
As I understand it there are a number of different reasons to have Fast Interrupts enabled, including differentiation of secure vs unsecure interrupt sources in ARM TrustZone. Also searching in the code base there seem to be a number of references to the FIQ in MTD, sound, and SPI code.
So my question is: why is CONFIG_FIQ removed just from removing "Sound card support" in the menuconfig? Does the i.MX6DL only use FIQ for audio purposes? Seems there are other uses.