[PATCH v2] clk: fix clk_get_rate() documentation

[Giulio Benetti]

On 2/22/21 8:13 PM, Heinrich Schuchardt wrote:
> On 2/14/21 4:49 AM, Jesse T wrote:
>> 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
>>>>
>>>>
> 
> Cc: Lukasz Majewski <lukma at denx.de>
> Lukasz is maintainer for CLOCK.

Ah thank you that's right. I've missed it because 
./scripts/get_maintainer.pl didn't list him.

-- 
Giulio Benetti
Benetti Engineering sas