On Sun, 2003-03-09 at 14:18, Kevin B. Hendricks wrote: > Hi Ben, > > > There is currently no solution for external flat panels, I simple don't > > know how backlight is controlled on these. > > On a lark I installed pmud and pbbuttonsd but all I ended up with was a > completely dark screen for my login prompt. I was blindly able to go to > /etc/rc.d/init.d/ and do a rm *pmu* and then reboot. > > I find it strange that pmud and pbbuttonsd works on an imac and not other > desktops. If I remember, the code in the Radeon driver special cases the > LCD backlight code differently from the DFP.
I don't know how well work on iMac, I suppose they only deal with machine sleep (which _is_ supported on CRT iMacs, but not on flat panel ones for now). I have figured out how to control the IVAD controller which controls the brightness, contrast and geometry of the CRT display of iMacs and eMacs (except the very first iMac model which use a different chip but I know how to drive it as well), it's fortunately all (almost...) in Darwin. I'm trying to figure out the best way to expose this to userland though. I think I'll simply expose the PMU and Cuda i2c busses via the linux i2c framework and write a userland cmdline tool to access those parameters. Regarding DFP displays, it _seems_ the backlight is not controlled by the video chip, at least I found nothing to tweak the backlight with the TMDS_* registers or FP_* registers like there is for LVDS, but I may be wrong. Though I suspect it's either driven via some i2c bus (same used for EDID) or via USB. I'll try to do some tracing of the MacOS 9 code with an Apple 15" TFT ADC flat panel on a Cube with radeon next week. N.B. I'm still looking for some specs about DDC and EDID format if anybody have that at hand... > Perhaps both are controlled in the same way? > > Is there any similar piece of Darwin source I should be looking at to > figure this out? > > Thanks, > > Kevin -- Benjamin Herrenschmidt <[EMAIL PROTECTED]>