return codes

On investigating call sites for 'return' in drivers/staging/ks7010/ it can be seen that a number of functions us *custom* (positive) integers to indicate error. Notwithstanding that they are positive, is this ok for code in the kernel (i.e in order to get out of staging does this need to be changed)? Functions in question have internal linkage and the error code is used for debug messages. Should these be A) left alone B) made negative C) changed to use standard error codes (i.e -ENOMEM etc) thanks, Tobin.