Comment 246 for bug 568611

Is there a way to have a finer control of the screen brightness?

I have been using the kamal~mjgbacklight kernels for
the /sys/class/backlight/intel_backlight control in my Dell
Studio 1558 since last spring. I now have the kamal~mjgbacklight
kernel in my Sony Vaio All-in-One with 22" display. Both systems
have the 1920x1080 screens and Core i3 CPU with the i915 driver and
the Sony has the same issue with the backlight as the Dell.

Both of these systems have a blinding bright screen and
the intel_backlight control solves those problems. Now I
have tried the acpi_video0 control on the newer kernels and the
result is not good enough.

My current kernel is linux 3.0 and I have both intel_backlight and
acpi_video0. The maximum brightness on the Dell is 4882 for the
intel_backlight and 15 for the acpi_video0 except the acpi_video0
doesn't seem to work for the Dell. The Sony has maximum brightness
of 4687 with the intel_brightness and maximum of 8 with the
acpi_video0 and both can used at the same time. Here is the problem
with the Sony:

ACPI INTEL
0 1066
1 1396
2 1874
3 2334
.
.
8 4687

The settings for acpi_video0 at 4,5,6,7 are too bright for my eyes
to check the numbers and cause a type of blindness after a while.
Most of the time I use the brightness setting of between 300 and 500
with the intel_backlight control because the setting for 0 or 1 on
the acpi_video0 control is just too bright for my eyes.

The problem is the same with Windows 7 where the minimum brightness
is too bright. I think the acpi configuration might be finding the
same settings as for Windows and that is the problem. My solution
is to continue to use the intel_backlight control from the
kamal~mjgbacklight kernel.

Am I missing something here? Are there going to be any more fixes to
the brightness control? I am about to try the linux 3.1 kernel except
doubt the acpi_video0 will give a fine enough control of the brightness.
Should I continue to use the kamal~mjgbacklight fixing kernel forever?

I really like my Dell and my Sony when using the intel_backlight
brightness control and can't stand them with the acpi_video0 control.

Double thanks for Kamal-