Whats the relation between FatFs middleware (ff and the low layer implementation) and sd_diskio?
To my knowledge, FatFs requires some low layer drivers in orden to work, and those APIs must be provided by the user. In UM1721 is pretty well described: "The FatFs Middleware solution provides low level disk I/O drivers for some supported disk drives (RAMDisk, microSD, USBDisk). An additional interface layer diskio.c has been added to add/remove dynamically physical media to the FatFs module, providing low level disk I/O functions".
However, I've seen some tutorials where sd_diskio and bsp_driver_sd are altered, in order for the application to support DMA transfer. I really dont get how ff functions (f_mount, f_read, etc) and diskio functions (disk_read, disk_write, etc) are related to that BSP layer and that sd_diskio file. Where are those functions called in the low level disk drivers?