[PATCH] UBUNTU: SAUCE: samsung-laptop: disable in UEFI mode

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

BugLink: https://launchpad.net/bugs/1040557

Disable this driver if we've booted in UEFI mode as some Samsungs
seem to get bricked and are rendered unbootable when this driver
tries to poke around the BIOS controls when in UEFI.

== SRU Justification ==

A whole bunch of Samsung laptops in UEFI mode get bricked and
become unbootable when using the samsung-laptop driver. The driver
only should poke around with the firmware in traditional BIOS mode
rather than in UEFI mode.  To prevent bricking machines we should
disable this driver (which only works in non-UEFI mode anyway)
when we are using UEFI.

== Fix ==

This SAUCE patch detects if we booted in UEFI and if so exits
early in the init stage with -ENODEV.

== Impact ==

Without this fix users are seeing their machines getting bricked.

== Test Case ==

I haven't tested this on UEFI enabled machines.  Joseph Salisbury
boot tested this on a BIOS enabled machine on Raring and the driver
loaded, so we know there is no regression potential for BIOS mode
machines.

A testcase is to boot the machine. In UEFI mode the machine locks
up and a subsequent reboot results in a bricked machine. With the
fix the driver won't load and the machine should be OK.

Colin Ian King (1):
  UBUNTU: SAUCE: samsung-laptop: disable in UEFI mode

 drivers/platform/x86/samsung-laptop.c |    4 ++++
 1 file changed, 4 insertions(+)

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1.7.9.5