Re: [PATCH] LED control

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 09/05/2010 08:43 PM, Andy Walls wrote:
> On Sun, 2010-09-05 at 15:54 +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 09/05/2010 10:56 AM, Jean-Francois Moine wrote:
>>> On Sun, 05 Sep 2010 09:56:54 +0200
>>> Hans de Goede<hdegoede@redhat.com>   wrote:
>>>
>>>> I think that using one control for both status leds (which is what we
>>>> are usually talking about) and illuminator(s) is a bad idea. I'm fine
>>>> with standardizing these, but can we please have 2 CID's one for
>>>> status lights and one for the led. Esp, as I can easily see us
>>>> supporting a microscope in the future where the microscope itself or
>>>> other devices with the same bridge will have a status led, so then we
>>>> will need 2 separate controls anyways.
>>>
>>> Hi Hans,
>>>
>>> I was not thinking about the status light (I do not see any other usage
>>> for it), but well about illuminators which I saw only in microscopes.
>>>
>>
>> Ah, ok thanks for clarifying. For some more on this see p.s. below.
>>
>>> So, which is the better name? V4L2_CID_LAMPS? V4L2_CID_ILLUMINATORS?
>>
>> I think that V4L2_CID_ILLUMINATORS together with a comment in the .h
>> and explanation in the spec that this specifically applies to microscopes
>> would be good.
>
> I concur with ILLUMINATORS.  The word makes it very clear the control is
> about actively putting light on a subject.  A quick Goggle search shows
> that the term 'illuminator" appears to apply to photography and IR
> cameras as well.
>
>
>> Regards,
>>
>> Hans
>>
>> p.s.
>>
>> I think it would be good to have a V4L2_CID_STATUS_LED too. In many drivers
>> we are explicitly controlling the led by register writes. Some people may very
>> well prefer the led to always be off. I know that uvc logitech cameras have
>> controls for the status led through the extended uvc controls. Once we have
>> a standardized LED control, we can move the logitech uvc cams over from
>> using their own private one to this one.
>
> I saw two use cases mentioned for status LEDs:
>
> 1. always off
> 2. driver automatically controls the LEDs.
>
> Can't that choice be handled with a module option

Sure, just like all other v4l2 controls could be a module option, that is
not very userfriendly though.

, is there a case where
> one needs more control?

Not really.

Regards,

Hans