Hi, I currently try to develop a device driver for the National Instruments X-series DAQ cards. These are PCIe cards with real-time capable analog and digital i/o modules. All of these are configured through many registers in combination with dma. I thought of using regmap-mmio to configure all these registers. However the register size is not homogenous throughout the device. Depending on the submodule they use 8, 16, 32 or 64 bit registers. Would it be a problem to use several regmaps in parallel, one per register size? Assuming this would work I've seen the regmap_fields API. It would be nice to use as it would hide the different regmaps inside the regmap_field struct. However the device has many registers and even more fields (didn't count, but many hundred). Is it ok to allocate this many regmap_fields dynamically? I am wondering as all information except the regmap pointer is static. Another question for the same device: The device has the actual output modules and a custom DMA chip (NI CHInCh). As the DMA seems to be a special component of the chip, should I still try to integrate it into the dmaengine framework? And if so, how do I register the modules to have the pci device shared between DMA and DAQ components? Thanks, Hendrik