Hello,
We want to control the backlight for external display from Windows On Arm running on our custom i.MX8M board.
Here is our understanding about software that are involved in the backlight control below.
-ACPI gives us standard method to adjust the backlight.
-Laptop PC often uses ACPI to control the backlight.
-Backlight is controled by sending a command from Windows to UEFI.
-Windows must have a driver and configuration to control the backlight.
Here is our questions about the backlight control on running Windows On Arm on i.MX8M.
(1) We see the following control flow in the document of uefi.
Which is correct understanding about control flow from Windows to the actual hardware(i.MX8M)?
a) Calling a driver directly? (Backlight driver is needed?)
b) Backlight is controlled via ACPI?
c) Both a) and b) works toghether?
(2) If we trun off or on the external display from Windows, Which is correct understanding about control flow?
a) Calling a display driver directly to turn off or on the external display?
b) It is controlled via ACPI?
c) Both a) and b) works toghether?
(3) We need to control the backlight along with turning off or on the external display.
It means that a fucntion for turning on and off the backlight must be integrated in the display driver.
In this case, driver uses the method in above question (1) to change the luminance?
Regards,
Norihiro Michigami
