On Tue, Apr 17, 2018 at 05:18:26PM +0200, Hans de Goede wrote:
> Commit 5928c281524f ("ACPI / video: Default lcd_only to true on Win8-ready
> and newer machines") made only_lcd default to true on all machines where
> acpi_osi_is_win8() returns true, including laptops.
>
> The purpose of this is to avoid the bogus / non-working acpi backlight
> interface which many newer BIOS-es define on desktop machines.
>
> But this is causing a regression on some laptops, specifically on the
> Dell XPS 13 2013 model, which does not have the LCD flag set for its
> fully functional ACPI backlight interface.
>
> Rather then DMI quirking our way out of this, this commits changes the
> logic for setting only_lcd to true, to only do this on machines with
> a desktop (or server) dmi chassis-type.
>
> Note that we cannot simply only check the chassis-type and not register
> the backlight interface based on that as there are some laptops and
> tablets which have their chassis-type set to "3" aka desktop. Hopefully
> the combination of checking the LCD flag, but only on devices with
> a desktop(ish) chassis-type will avoid the needs for DMI quirks for this,
> or at least limit the amount of DMI quirks which we need to a minimum.
>
> Cc: James Hogan <jhogan@xxxxxxxxxx>
> Reported-by: James Hogan <jhogan@xxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Tested on Dell XPS13 (2013).
Tested-by: James Hogan <jhogan@xxxxxxxxxx>
Thanks
James
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