On Fri, Apr 06, 2012 at 11:42:18AM +0200, Corentin Chary wrote: > On Tue, Mar 27, 2012 at 1:21 PM, Matthew Garrett <mjg59@xxxxxxxxxxxxx> wrote: > > On Tue, Mar 27, 2012 at 11:11:18AM +0200, Corentin Chary wrote: > >> Matthew, is this one ok ? I really hope this patch can go in 3.4 so we > >> don't introduce a regression for old laptops. > > > > Yes, I've got this now. > > > > Thanks, > > > A user just found a DSDT which is broken by this way of doing things > (this is not really a regression since it was also broken before). > > _BCL contains a wierd "Or (VDRV, 0x02, VDRV)". > So if you call _BLC once (video.ko will), it set a flag that affect > the behavior of all backlight related stuff, and it breaks > samsung-laptop's backlight even if samsung-laptop unload the acpi > backlight. > Using acpi_backlight=vendor solves that since it prevents the module > from being loaded. My previous patch also fix that since it use > acpi_backlight= mechanism. > > Do you think using acpi_backlight=vendor is a good enought solution > here ? Should we use my first patch instead ? I've recently noticed another problem with using acpi_video_unregister() to disable known broken backlights -- another module might call acpi_video_register() and make it reappear. i915 does this, so when I EFI boot the MacBook Pro 8,2 the acpi backlights reappear (under a BIOS compatible boot the Intel GPU doesn't show up on the bus). So Corentin's solution does seem like a better way to go, or else something similar that forces the ACPI video driver to behave as with acpi_video=vendor. Seth -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
