[PATCH v2] clk: fix clk_get_rate() documentation

[Giulio Benetti <giulio.benetti@benettiengineering.com>]

Hi Jesse,

> Il giorno 14 feb 2021, alle ore 03:58, Jesse T <mr.bossman075@gmail.com> ha scritto:
> 
> ?
> This looks good to me, and helps beginners like me. As for the function itself, i have 2 concerns: If it does return a negative value why is it unsigned, if it is in fact signed that a clock above 2.2Ghz is a negative number.

I was worried too at first sight but if you try to check negative numbers you see that -1 is 0xFFFFFFFF so in the worst case you only loose 4095 numbers from the maximum, try to check with hex calculator. And that is the trick.

> As for the IS_ERR_VALUE macro there still is a chance that it will error if the clock just so happens to be 2^31  through 2^31 + number of err values.

This is answered from above and IS_ERR_VALUE is a very contracted macro that basically let you to keep value NOT valid if (0 > value > 4095). 

> Just voicing my concerns i assume as i learn more about uboot, linux,rtos's and different programs there will be minor issues like this. 

Sure, no problem :-)

Giulio

> 
>> On Sat, Feb 13, 2021 at 9:17 PM Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:
>> Improve clk_get_rate() @return documentation that otherwise is a bit
>> ambiguous. At the moment I expect to return 0 as error since the return
>> type is 'ulong', instead the function really returns negative value in
>> case the corresponding function pointer is null and returns 0 if the clock
>> is invalid.
>> 
>> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
>> ---
>> V1->V2:
>> * previous comment was wrong, this function returns negative value, so let's
>>   improve it's @return documentation as suggested by Simon Glass
>> ---
>>  include/clk.h | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/include/clk.h b/include/clk.h
>> index ca6b85fa6f..5a8c7244d0 100644
>> --- a/include/clk.h
>> +++ b/include/clk.h
>> @@ -344,7 +344,8 @@ int clk_free(struct clk *clk);
>>   *
>>   * @clk:       A clock struct that was previously successfully requested by
>>   *             clk_request/get_by_*().
>> - * @return clock rate in Hz, or -ve error code.
>> + * @return clock rate in Hz on success, 0 for invalid clock, or -ve error code
>> + *        for other errors.
>>   */
>>  ulong clk_get_rate(struct clk *clk);
>> 
>> -- 
>> 2.25.1
>>