Hi Tim, AFAIK NuttX doesn't have a standard way to do it. It is normally done at board level (do a "git grep backlight" inside boards/ to see some examples).
A proper way to do that should be implementing a backlight subsystem, like a subset of Linux backlight subsystem: https://docs.kernel.org/gpu/backlight.html I think you could create a simple char device driver (at drivers/lcd/backlight.c) that will receive IOCTLs to set the backlight dimming. Best Regards, Alan On Wed, Jan 3, 2024 at 3:03 PM Tim Hardisty <timhardist...@gmail.com> wrote: > My SAMA5 board has an LCD with variable brightness (pwm controlled). > > arch/arm/src/chip/sam_lcd.c has a function called "sam_backlight) that > takes a level value, but it appears to be local to that file, and the > only call to it is in the LCD init functions in that file, complete with > a comment that says: > > /REVISIT: Backlight level could be dynamically adjustable/ > > That's what I need. > > But from an app perspective I can't get my mind around what the right > function call would be to ripple that down to something low level and > board specific. So if I change the processor, for example, the app will > still work and not rely (for example) on board ioctls. > > Can someone point me in the direction of the "right" way to handle this, > please? Once I know the "flow" I can work out how and where it is best > to expose the right function. > > Thanks! > >
