https://bugs.freedesktop.org/show_bug.cgi?id=65377
Priority: medium Bug ID: 65377 Assignee: dri-devel@lists.freedesktop.org Summary: Backlight control via /sys/class/backlight/radeon_bl0 not working Severity: normal Classification: Unclassified OS: Linux (All) Reporter: bastian.triller@gmail.com Hardware: x86-64 (AMD64) Status: NEW Version: XOrg CVS Component: DRM/Radeon Product: DRI
This is a Macbook pro 8,2 with an Intel HD Graphics 3000 [8086:0116] and an AMD Radeon HD 6750M [1002:6741]. The backlight interface in /sys/class/backlight/radeon_bl0 does not work. Echoing to "brightness" does not change the brightness of the Monitor. There is also an apple_gmux interface, which works though. I've bound xbacklight to the brightness keys to control the brightness, but it looks like it's confused about which interface it should use: $ xbacklight -inc 5 No outputs have backlight property
When I disable the Radeon card on boot and use the Intel card, xbacklight works.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #1 from Alex Deucher agd5f@yahoo.com --- If you are booting in EFI mode, does it work if you boot in legacy bios mode? Since it's a mac, it probably requires some mac specific hack.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #2 from Bastian Triller bastian.triller@gmail.com --- (In reply to comment #1)
If you are booting in EFI mode, does it work if you boot in legacy bios mode? Since it's a mac, it probably requires some mac specific hack.
I'm booting via EFI stub. I'm not sure how to boot the bios emulation mode. Is it possible to plug in a usb stick with a "normal" live system to boot in emulation mode?
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #3 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #2)
I'm booting via EFI stub. I'm not sure how to boot the bios emulation mode. Is it possible to plug in a usb stick with a "normal" live system to boot in emulation mode?
I'm not sure.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #4 from Henri Verbeet hverbeet@gmail.com --- I think it depends a bit on the specific model, but many Macs will only boot EFI from USB. Refind (http://www.rodsbooks.com/refind/index.html) is potentially a way around that, although I'm not entirely sure if that counts as booting in EFI mode or in BIOS mode.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #5 from Alex Deucher agd5f@yahoo.com --- I believe the only way to control the backlight on the macs with multiple GPUs is via the gmux driver. Seems to be a mac specific thing.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #6 from Bastian Triller bastian.triller@gmail.com --- Booting a dd'ed image did not work. I'll have to find a disc to test it.
Looking into the xbacklight I saw that xbacklight tries to find a Backlught property on the output. xrandr lists this property on the intel output, but not on the radeon output.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #7 from Bastian Triller bastian.triller@gmail.com --- The problem also exists if I boot in bios mode.
I didn't mention that, when using the intel card there only is the apple_gmux interface.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
--- Comment #8 from Alex Deucher agd5f@yahoo.com --- Created attachment 80624 --> https://bugs.freedesktop.org/attachment.cgi?id=80624&action=edit don't register a radeon backlight
This patch should skip adding a radeon backlight interface on your mac.
https://bugs.freedesktop.org/show_bug.cgi?id=65377
Bastian Triller bastian.triller@gmail.com changed:
What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |FIXED
--- Comment #9 from Bastian Triller bastian.triller@gmail.com --- yes, /sys/class/backlight/radeon_bl0 device is gone.
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