[Bug 84561] [ivb] Intel backlight does not adjust, but only turns on/off in kernel 3.16 on Samsung 880Z5E laptop

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=84561

--- Comment #22 from brent s. <brent.saner at gmail.com> ---
Per Bug #84221, the following patch restores backlight functionality for me:

diff --git drivers/acpi/video.c drivers/acpi/video.c
index 9d75ead..fcec2b1 100644
--- drivers/acpi/video.c
+++ drivers/acpi/video.c
@@ -504,6 +504,15 @@ static struct dmi_system_id video_dmi_table[] __initdata =
{
                DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
                },
        },
+
+       {
+        .callback = video_disable_native_backlight,
+        .ident = "SAMSUNG 870Z5E/880Z5E/680Z5E",
+        .matches = {
+               DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+               DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
+               },
+       },      
        {}
 };


I'm assuming it will work for you based on the .ident/.matches (based on the
dmidecode attached to the ticket). It essentially disables the "intel native
backlight" functionality that was introduced in 3.16?.something?


Note that I'm testing this against a vanilla kernel (I'm using ArchLinux, not
Ubuntu) and using the following .config:

https://projects.archlinux.org/svntogit/packages.git/plain/trunk/config.x86_64?h=packages/linux

Your userspace mileage may vary, as I don't know how well Ubuntu plays with a
non-downstream-patched kernel.

Anyways, beerz for Aaron Lu for finding a fix, and I'm assuming it'll be pushed
upstream soon.

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