On Mon, 2008-01-14 at 16:01 +0000, Rui Paulo wrote: > I have the backlight module ready to be committed (needs approval > first), but it would be great if we could create a general backlight > API. I have some initial ideas, but needs a bit more thought. > > Also, xrandr on (7.3 with "intel" video driver) seems to be able to > control the LCD backlight on MacBooks, but it seems bogus: > > % xrandr --prop > Screen 0: minimum 320 x 200, current 1280 x 800, maximum 1280 x 1280 > VGA disconnected (normal left inverted right x axis y axis) > LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 286mm x 179mm > EDID_DATA: > 00ffffffffffff0006105b9c00000000 > 0e100103801d12780a87f594574f8c27 > 27505400000001010101010101010101 > 010101010101bc1b00a0502017303020 > 36001eb3100000190000000100061020 > 00000000000000000a20000000fe004c > 544e31333357310000000a20000000fc > 00436f6c6f72204c43440a20202000c6 > BACKLIGHT: 296 (0x00000128) range: (0,296) > > I don't really know about how exactly this control works, because: > > 1) the range is wrong. > 2) setting values with xrandr --output LVDS --set BACKLIGHT <value>, > doesn't seem to be doing anything good. It just sets a high and low > value for the backlight brigthness. > > If anyone knows anything about this, I would appreciate if you could > step forward. > > There's another problem: xv (try it with mplayer -vo xv) seems to be > setting the backlight value on initialization. So, if you start Xorg > with backlight value of 50, then reduce it to 20 and after that try > to play a video with mplayer, the backlight value seems to come back > to 50. There are very strange interactions between xrandr and my own > backlight control kernel module. It would be great to disable xrandr's > backlight control, at least. > > Regards. > -- > Rui Paulo > I have the backlight module ready to be committed (needs approval > first), but it would be great if we could create a general backlight > API. I have some initial ideas, but needs a bit more thought. > > Also, xrandr on (7.3 with "intel" video driver) seems to be able to > control the LCD backlight on MacBooks, but it seems bogus: > > % xrandr --prop > Screen 0: minimum 320 x 200, current 1280 x 800, maximum 1280 x 1280 > VGA disconnected (normal left inverted right x axis y axis) > LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 286mm x 179mm > EDID_DATA: > 00ffffffffffff0006105b9c00000000 > 0e100103801d12780a87f594574f8c27 > 27505400000001010101010101010101 > 010101010101bc1b00a0502017303020 > 36001eb3100000190000000100061020 > 00000000000000000a20000000fe004c > 544e31333357310000000a20000000fc > 00436f6c6f72204c43440a20202000c6 > BACKLIGHT: 296 (0x00000128) range: (0,296) > > I don't really know about how exactly this control works, because: > > 1) the range is wrong. > 2) setting values with xrandr --output LVDS --set BACKLIGHT <value>, > doesn't seem to be doing anything good. It just sets a high and low > value for the backlight brigthness. That xrandr --prop output may be broken. My xlib fu is weak. > If anyone knows anything about this, I would appreciate if you could > step forward. > > There's another problem: xv (try it with mplayer -vo xv) seems to be > setting the backlight value on initialization. So, if you start Xorg > with backlight value of 50, then reduce it to 20 and after that try > to play a video with mplayer, the backlight value seems to come back > to 50. There are very strange interactions between xrandr and my own > backlight control kernel module. It would be great to disable xrandr's > backlight control, at least. I use xbacklight -set <percentage> to control backlight. Your issue with it flipping to only a high/low value may have been the one jbarnes fixed in git recently (apparently a low bit got redefined on us). -- Eric Anholt anholt_at_FreeBSD.org eric_at_anholt.net eric.anholt_at_intel.com
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