I'm using vendor commands (implemented in the setup callback function) to implement i2c register read/write to/from my FPGA. I was wondering: How does one normally report back to the host (PC) that the i2c transfer failed? I assumed that returning false from the Setup-Callback (in some examples used by some "isHandled"-logic) would do this, but apparently it's not. Furthermore I was unable to find what exactly is done with the value returned from the Setup-callback-function.
Would one simply implement an additional vendor command for reading back the result of the previous vendor command?