nb/i945/gma.c: Refactor panel setup

This reuses some of gm45 code to set up the panel.

Panel start and stop delays and pwm frequency can now be set in
devicetree.

Linux does not make the difference between 945gm and gm45
for panel delays, so it is safe to assume the semantics of those
registers are the same.

The core display clock is computed according to "Mobile Intel® 945
Express Chipset Family" Datasheet.

This selects Legacy backlight mode since most targets have some smm
code that rely on this.

This sets the same backlight frequency as vendor bios on Thinkpad X60
and T60.

A default of 180Hz is selected for the PWM frequency if it is not
defined in the devicetree, this might be annoying for displays that
are LED backlit, but is a safe value for CCFL backlit displays.

Change-Id: I1c47b68eecc19624ee534598c22da183bc89425d
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/18141
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions