On 10/01/2018 11:27 AM, Helmut Grohne wrote:
> On Fri, Sep 28, 2018 at 04:00:17PM +0200, Hans Verkuil wrote:
>> On 09/25/2018 12:14 PM, Sakari Ailus wrote:
>>> +/* V4L2 control unit prefixes */
>>> +#define V4L2_CTRL_PREFIX_NANO -9
>>> +#define V4L2_CTRL_PREFIX_MICRO -6
>>> +#define V4L2_CTRL_PREFIX_MILLI -3
>>> +#define V4L2_CTRL_PREFIX_1 0
>>
>> I would prefer PREFIX_NONE, since there is no prefix in this case.
>>
>> I assume this prefix is only valid if the unit is not UNDEFINED and not
>> NONE?
>
> Why should it? The prefix is concerned with rescaling a value prior to
> presenting it to a user. Even a unitless quantity or a value of
> undefined unit can be reasonably scaled. Displaying a unit and scaling
> look like orthogonal concepts to me.
What's the point? If I have a unit-less control with values 1-1000, then
what would a prefix 'milli' tell me as a user? Why would 0.001-1 be better
compared to 1-1000?
Without a unit it is just an integer range and scaling is meaningless.
>
>> Is 'base' also dependent on a valid unit? (it doesn't appear to be)
>
> I'd argue it should not depend on a valid unit like the prefix.
I think I agree with that, although I am dubious about the value of the
base field as I commented on elsewhere.
Regards,
Hans
