[PATCH v2] clk: fix clk_get_rate() documentation

[Jesse T]

Awesome, thanks! I must have forgotten how twos complement works for a
sec...

On Sat, Feb 13, 2021 at 10:17 PM Giulio Benetti <
giulio.benetti at benettiengineering.com> wrote:

> Hi Jesse,
>
> Il giorno 14 feb 2021, alle ore 03:58, Jesse T <mr.bossman075 at 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 at 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 at 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
>>
>>