Re: linux-next 20160512 - ACPI issue with screen brightness

From	Aaron Lu <aaron.lu@intel.com>
Newsgroups	linux.kernel
Subject	Re: linux-next 20160512 - ACPI issue with screen brightness
Date	2016-05-20 09:20 +0200
Message-ID	<rAMT0-2uP-17@gated-at.bofh.it> (permalink)
References	(1 earlier) <rzUfT-ZV-3@gated-at.bofh.it> <rAF57-5TT-13@gated-at.bofh.it> <rAIZ4-7x-17@gated-at.bofh.it> <rALtU-1xW-5@gated-at.bofh.it> <rAMJj-2rs-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, May 20, 2016 at 03:02:08AM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Fri, 20 May 2016 13:45:30 +0800, Aaron Lu said:
> > On 05/20/2016 11:05 AM, Valdis.Kletnieks@vt.edu wrote:
> > > On Thu, 19 May 2016 18:53:17 -0400, Valdis.Kletnieks@vt.edu said:
> > >
> > >>>> next-20160512 sets the screen brightness to about 40%-ish or so, rather
> > >>>> than the 100% intensity I want.
> >
> > Do you mean after boot, the screen brightness is now 40% instead of the
> > previous 100%? Are you using a GUI?
> 
> Nope, even the very first line of output from initramfs is dim, and if I then
> reboot and go into the BIOS settings, the screen intensity is at 40%. While
> it's rebooting, the Dell bios splash will start off bright and then suddenly
> dim down.
> 
> With the patches reverted:
> 
> [/sys/class/backlight/acpi_video0] grep . *bright*
> actual_brightness:95
> brightness:95
> max_brightness:95
> 
> And the weird part inside the kernel - on a kernel that has the problem,
> /sys/class/backlight is *empty* - only '.' and '..' entries.
> 
> No, I don't understand why the acpi_video0 entry isn't created when that
> commit is in place.

The commit probably makes acpi_video_init_brightness bail out for some
reason, adding debug prints under those "if (result)" in
acpi_video_init_brightness should help to identify where it goes wrong.

And your acpidump please, thanks.

Thread

linux-next 20160512 - ACPI issue with screen brightness Valdis Kletnieks <Valdis.Kletnieks@vt.edu> - 2016-05-17 20:50 +0200
  Re: linux-next 20160512 - ACPI issue with screen brightness "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-17 23:00 +0200
    Re: linux-next 20160512 - ACPI issue with screen brightness Valdis.Kletnieks@vt.edu - 2016-05-20 01:00 +0200
      Re: linux-next 20160512 - ACPI issue with screen brightness Valdis.Kletnieks@vt.edu - 2016-05-20 05:10 +0200
        Re: linux-next 20160512 - ACPI issue with screen brightness Aaron Lu <aaron.lu@intel.com> - 2016-05-20 07:50 +0200
          Re: linux-next 20160512 - ACPI issue with screen brightness Valdis.Kletnieks@vt.edu - 2016-05-20 09:10 +0200
            Re: linux-next 20160512 - ACPI issue with screen brightness Aaron Lu <aaron.lu@intel.com> - 2016-05-20 09:20 +0200
              Re: linux-next 20160512 - ACPI issue with screen brightness Aaron Lu <aaron.lu@intel.com> - 2016-05-20 09:40 +0200
              Re: linux-next 20160512 - ACPI issue with screen brightness Aaron Lu <aaron.lu@intel.com> - 2016-05-21 05:30 +0200
                [PATCH] ACPI / Thermal / video: fix max_level incorrect value Aaron Lu <aaron.lu@intel.com> - 2016-05-21 10:00 +0200
                Re: [PATCH] ACPI / Thermal / video: fix max_level incorrect value Aaron Lu <aaron.lu@intel.com> - 2016-05-25 07:20 +0200
                Re: [PATCH] ACPI / Thermal / video: fix max_level incorrect value Valdis.Kletnieks@vt.edu - 2016-05-26 03:50 +0200
                Re: [PATCH] ACPI / Thermal / video: fix max_level incorrect value Aaron Lu <aaron.lu@intel.com> - 2016-05-26 07:20 +0200
                Re: [PATCH] ACPI / Thermal / video: fix max_level incorrect value "Zhang, Rui" <rui.zhang@intel.com> - 2016-05-27 02:50 +0200

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