Messages in this thread | | | From | Jani Nikula <> | Subject | Re: [PATCH 2/2] ACPI / video / i915: Remove ACPI backlight if firmware expects Windows 8 | Date | Wed, 11 Sep 2013 11:45:19 +0300 |
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On Wed, 11 Sep 2013, Aaron Lu <aaron.lu@intel.com> wrote: > It is possible the i915 driver decides not to register a backlight > interface for the graphics card for some reason(memory allocation failed > or it knows the native control does not work on this card or whatever), > so I would prefer let i915 tell ACPI video that it has registered a > native backlight control interface as Jani has said. > > Then together with the video.use_native_backlight, we can register or > not register ACPI video backlight interface accordingly. Or rather, we > can simply not register ACPI video backlight interface for Win8 systems > as long as i915 indicates that it has native backlight control(if the > native control is broken, i915 should fix it or blacklist it so that > i915 will not indicate it has native backlight control and ACPI video > will continue to register its own). > > How does this sound?
Sounds good to me.
Before plunging forward, have you observed any difference between the boot modes? We have reports [1] that the backlight behaviour is different with UEFI vs. UEFI+CSM or legacy boot. So I'm wondering if the acpi_gbl_osi_data >= ACPI_OSI_WIN_8 check in patch 2/2 is the whole story.
Further, if we tell the BIOS we're Windows 8 to use the tested BIOS code paths, what guarantees do we have of UEFI+CSM or legacy boots working?
BR, Jani.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=47941#c96
-- Jani Nikula, Intel Open Source Technology Center
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