On Mon, Apr 23, 2012 at 05:38:27PM +0200, Carsten Emde wrote: > On 04/23/2012 05:22 PM, Daniel Vetter wrote: > >On Mon, Apr 23, 2012 at 05:06:53PM +0200, Carsten Emde wrote: > >>On 04/23/2012 04:22 PM, Daniel Vetter wrote: > >>>On Mon, Apr 23, 2012 at 04:00:23PM +0200, Carsten Emde wrote: > >>> [..] > >>>The idea was to boot with kms and see whether any of these values would > >>>restore the backlight. Writing to CTL1 should change anything in CTL2. > >>Ah, sorry, ok. Removed the quirk again and tested the various settings: > >> > >>-> Initial screen: dark > >> > >># intel_reg_write 0x61250 0x80000000 > >>Value before: 0xE0000000 > >>Value after: 0x80000000 > >>-> Still dark > >> > >># intel_reg_write 0x61250 0xa0000000 > >>Value before: 0x80000000 > >>Value after: 0xA0000000 > >>-> Still dark > >> > >># intel_reg_write 0x61250 0x90000000 > >>Value before: 0xA0000000 > >>Value after: 0x90000000 > >>-> BACKLIGHT ON! > >> > >># intel_reg_write 0x61250 0xb0000000 > >>Value before: 0x90000000 > >>Value after: 0xB0000000 > >>-> Still ON. > > > >Neat. Let's test two more: > > > ># intel_reg_write 0x61250 0xd0000000 > ># intel_reg_write 0x61250 0xc0000000 > Here we go. > > -> Initial screen: dark > > # intel_reg_write 0x61250 0xd0000000 > Value before: 0xE0000000 > Value after: 0xD0000000 > -> BACKLIGHT ON! > > # intel_reg_write 0x61250 0xc0000000 > Value before: 0xD0000000 > Value after: 0xC0000000 > -> Dark again. Ok, so the polarity bit does work as advertised. But I still don't understand how your machine works, so assuming your machine has backlight control keys, please boot with kms disabled and grab the both registers values for maximal brightness and minimal brightness. Then reconfigure the backlight with # intel_reg_write 0x61250 0x90000000 and check how the behaviour changes. Somehow we lose something when setting up drm/i915, but atm I can't figure out what yet. Thanks, Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
