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    samsung-laptop: Add use_native_backlight quirk, and enable it on some models · 4690555e
    Hans de Goede 提交于
    Since kernel 3.14 the backlight control has been broken on various Samsung
    Atom based netbooks. This has been bisected and this problem happens since
    commit b35684b8 ("drm/i915: do full backlight setup at enable time")
    
    This has been reported and discussed in detail here:
    http://lists.freedesktop.org/archives/intel-gfx/2014-July/049395.html
    
    Unfortunately no-one has been able to fix this. This only affects Samsung
    Atom netbooks, and the Linux kernel and the BIOS of those laptops have never
    worked well together. All affected laptops already have a quirk to avoid using
    the standard acpi-video interface and instead use the samsung specific SABI
    interface which samsung-laptop uses. It seems that recent fixes to the i915
    driver have also broken backlight control through the SABI interface.
    
    The intel_backlight driver OTOH works fine, and also allows for finer grained
    backlight control. So add a new use_native_backlight quirk, and replace the
    broken_acpi_video quirk with this quirk for affected models. This new quirk
    disables acpi-video as before and also stops samsung-laptop from registering
    the SABI based samsung_laptop backlight interface, leaving only the working
    intel_backlight interface.
    
    This commit enables this new quirk for 3 models which are known to be affected,
    chances are that it needs to be used on other models too.
    
    BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1094948 # N145P
    BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1115713 # N250P
    Reported-by: Bertrik Sikken <bertrik@sikken.nl> # N150P
    Cc: stable@vger.kernel.org # 3.16
    Signed-off-by: NHans de Goede <hdegoede@redhat.com>
    Signed-off-by: NDarren Hart <dvhart@linux.intel.com>
    4690555e
samsung-laptop.c 41.2 KB