This patch makes the behaviour of the intel_backlight backlight device consistent to e.g. acpi_videoX: When writing the value 0, the set brightness makes the panel content barely readable instead of turning the backlight off. This matches the expectations of user space (e.g. kde-workspace or the Intel X11 driver), which expects that it can use intel_backlight as a drop-in replacement for acpi_videoX. As BIOSes written for Windows 8 support seem to expect the display driver taking care of the brightness control instead of ACPI methods (see [1]), I would expect quite a number of people (like me ;) ) having the need of using intel_backlight instead of acpi_videoX. A quick Google search indicated that most people are confused by the current behaviour, so I think it's a good idea to make the default behaviour somehow match acpi_videoX.
Regards,
Danny
[1] https://bugzilla.kernel.org/show_bug.cgi?id=55071
Danny Baumann (1): drm/i915: Allow specifying a minimum brightness level for sysfs control.
drivers/gpu/drm/i915/intel_panel.c | 48 ++++++++++++++++++++++++++++++++------ 1 file changed, 41 insertions(+), 7 deletions(-)