Questions on adding backlight support for the i915 driver

[Elizabeth Myers]

On 01/30/15 17:45, John Baldwin wrote:
> On Friday, January 30, 2015 04:45:45 PM Elizabeth Myers wrote:
>> On 01/30/15 09:17, John Baldwin wrote:
>>> Humm.  If the code is going to live in the drm driver, then I would
>>> start with hanging a sysctl off of the drm device itself.  (Each new-bus
>>> device_t has a sysctl ctx you can get to hang new nodes off of the
>>> device's node.)
>> I'm wondering if that's the correct place for it to live. So far it's
>> the only real place it *can* live that makes logical sense imho, unless
>> anyone has better ideas.
>>
>> This is awesome. As for upower, it should probably be patched to know
>> about other types of brightness sysctls if/when this is implemented.
> For now I think hanging it off of the device_t is fine.  It can be moved
> later if there is an urgent need.  However, I suspect that tools like upower 
> will need updating regardless of where it ends up living.
>

Now a more interesting question... the raw PCM backlight value used by
the hardware means that one can set the backlight to anything between 0
and a specific number. On my system, it's 4882, and yes, there is a
subtle difference between the values. Is it best to expose this as a
percentage, or just have a read-only sysctl for max values?

--
Cheers,
Elizabeth