2015-03-27 16:53 GMT+01:00 Hans Petter Selasky <h...@selasky.org>:

> On 03/27/15 16:01, Ranjan1018 . wrote:
>
>> This  patch exposes the backlight support  via a sysctl:
>>
>> set the backlight to 10%:
>>
>> # sysctl hw.dri.0.i915_backlight=10
>>
>> hw.dri.0.i915_backlight: 25 -> 10
>>
>> set the backlight to 50%:
>>
>> # sysctl hw.dri.0.i915_backlight=50
>>
>> hw.dri.0.i915_backlight: 10 -> 50
>>
>> decrease  the current backlight value:
>>
>> # sysctl hw.dri.0.i915_backlight=-1000
>>
>> hw.dri.0.i915_backlight: 50 -> 43
>>
>> increment the current backlight value:
>>
>> # sysctl hw.dri.0.i915_backlight=1000
>>
>> hw.dri.0.i915_backlight: 43 -> 51
>>
>> # sysctl hw.dri.0.i915_backlight=1000
>>
>> hw.dri.0.i915_backlight: 51 -> 60
>>
>> I am running this path on for about a week without issue.
>>
>> This path can be found at:
>> https://github.com/maurizio-emmex/i915_backlight_freebsd
>>
>> I thank Elizabeth Myers, elizabeth at interlinked dot me, for the idea of
>> adding the backlight support for the i915 driver and for the original
>> patch.
>>
>> Regards,
>> Maurizio
>>
>
> Maybe you want to use "CTLFLAG_RWTUN" so that it also can be set from
> /boot/loader.conf ?
>
> --HPS
>

The ability to set the backlight at startup may be useful. With this new
patch I expose two ways to do this:
- with the tunable "drm.i915.init_backlight" in /boot/loader.conf, just
after the driver initialization (eg.  drm.i915.init_backlight=20)
- with the OID "hw.dri.0.i915_backlight" in /etc/sysctl.conf as suggested
by Hans
I don’t know if setting the backlight with the tunable
"drm.i915.init_backlight" is useful, but I have already written the code
and is simple to remove it.
The patch file is i915_backlight.patch at
https://github.com/maurizio-emmex/i915_backlight_freebsd

Regards,
Maurizio
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