Re: drm2 regression: backlight adjustment on ivybridge no longer works

2015-01-27 7:38 GMT+01:00 Andrew Wilcox <AWilcox_at_wilcox-tech.com>:

> Ranjan1018 . sent: 26 January 2015 06:19:
> > 2015-01-24 23:25 GMT+01:00 Adrian Chadd <adrian_at_freebsd.org>:
> > > The backlight adjustment doesn't work on my ivybridge mobile laptop
> > > (Lenovo X230) after the dri update.
> > >
> > I have the same issue on my Samsung Ativ 2 laptop.
>
> I have a Sandy Bridge laptop (Apple MacBook Pro 8,2) - HD 3000:
>
> vgapci0_at_pci0:0:2:0:     class=0x030000 card=0x00db106b chip=0x01268086
> rev=0x09 hdr=0x00
>     vendor     = 'Intel Corporation'
>     device     = '2nd Generation Core Processor Family Integrated Graphics
> Controller'
>     class      = display
>     subclass   = VGA
>
> It is running:  FreeBSD pwyll.foxkit.us 11.0-CURRENT #1 r277781M: Mon Jan
> 26 18:41:15 CST 2015 root_at_pwyll.foxkit.us:/usr/obj/usr/src/sys/GENERIC
> amd64
>
> I have no issues using acpi_video's sysctls
> (hw.acpi.video.lcd0.brightness) to adjust backlight, though it does not
> have good granularity.  The stepping is about 7, so it goes as
> 13%..20%..27%..35%..etc.
>
> > > The "intel_backlight" program from intel-gpu-tools" also no longer
> > > changes the backlight value.
>
> This program works fine for me on both an older kernel (r277523) and this
> kernel (r277781), after applying some patches to allow the library to build
> on FreeBSD.  It also has better granularity (the stepping is 2-3).
>
> If there is anything I can do/run to aide in debugging why it works for me
> but not others, let me know.
>
> Best,
> Andrew
> --
> Andrew Wilcox, C/C++/Python developer, kernel hacker
> Blog:   http://blog.foxkit.us/  WWW: http://foxkit.us/
> GitHub:  https://github.com/awilfox
>
> Hi,
my Samsung laptop has an Intel IvyBridge:
vgapci0_at_pci0:0:2:0:     class=0x030000 card=0xc708144d chip=0x01668086
rev=0x09 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '3rd Gen Core processor Graphics Controller'
    class      = display
    subclass   = VGA

The regression was introduced in r277487.
The backlight adjustment works in FreeBSD 11.0-CURRENT r277395, r277486 but
not in r277487, r277534 and r277639.

Regards,
Maurizio