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From: Zhang Rui <rui.zhang at intel.com>
To: devel@acpica.org
Subject: Re: [Devel] Missing _BQC method
Date: Tue, 03 Jan 2017 11:42:20 +0800	[thread overview]
Message-ID: <1483414940.2320.35.camel@intel.com> (raw)
In-Reply-To: 8036e82a-c79b-6824-1245-bf5fb027a1fa@yahoo.com

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On Sun, 2017-01-01 at 17:01 -0500, Anthony Jenkins wrote:
> What may the OSPM assume/do about a missing _BQC (Brightness Query
> Current level) method?

_BQC is optional according to the latest ACPI spec.
I don't know about the others, but in Linux, the brightness level is
set to 100% during boot if _BQC is missing, and a cached value is used
to save the current brightness level. 

thanks,
rui
>   The last two HP ENVY laptops I owned do not have
> this method, and FreeBSD's acpi_video driver (currently) requires it
> to
> control screen brightness - unless I can assume _only_ the OSPM can
> set
> the screen brightness.  My current workaround is a patch to the DSDT
> to
> add a simple method that copies and returns a variable used by _BCM
> (Brightness Control Method).
> 
> Thanks in advance,
> 

             reply	other threads:[~2017-01-03  3:42 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-03  3:42 Zhang Rui [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-01-01 22:01 [Devel] Missing _BQC method Anthony Jenkins

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