Seeking advice on API return type inconsistency

[Andrew Goodbody]

Hi,

I was wondering what people's thoughts were on API return types. In 
particular there is this and other examples in include/clk-uclass.h

/**
  * get_rate() - Get current clock rate.
  * @clk:	The clock to query.
  *
  * This returns the current rate of a clock. If the clock is disabled, it
  * returns the rate at which the clock would run if it was enabled. The
  * following pseudo-code should hold::
  *
  *   disable(clk)
  *   rate = get_rate(clk)
  *   enable(clk)
  *   assert(get_rate(clk) == rate)
  *
  * Return:
  * * The rate of @clk
  * * -%ENOSYS if this function is not implemented for @clk
  * * -%ENOENT if @clk->id is invalid. Prefer using an assert instead, 
and doing
  *   this check in request().
  * * Another negative error value (such as %EIO or %ECOMM) if the rate 
could
  *   not be determined due to a bus error.
  */
ulong get_rate(struct clk *clk);


get_rate is declared as returning a ulong but the description says that 
it can return negative errors. A simple test of the return value for 
being less than 0 will always fail so errors can go undetected. Casting 
to a signed type seems less than ideal.

What is the best way to deal with this? Cast to a signed or update the 
API to be signed or...?

Andrew