There were two mistakes in the register-read-on-(un)blank approach.
- First, without proper register (un)locking the value read back will always
be zero, and this is what I missed entirely until just now. Due to this,
the logic could not be verified at all and I tried some bogus checks which
are completely stupid.
- Second, the LCD status bit will always be set to zero when the backlight
has been turned off. Reading the value back during unblank will disable the
LCD unconditionally, regardless of the state it is supposed to be in, since
we set it to zero beforehand.
So this is what we do now:
- create a new variable in struct neofb_par, and use that to determine
whether to read back registers (initialized to true)
- before actually blanking the screen, read back the register to sense any
possible change made through Fn key combo
- use proper neoUnlock() / neoLock() to actually read something
- every call to neofb_blank() determines if we read back next time: blanking
disables readback, unblanking (FB_BLANK_UNBLANK) enables it
This should give us a nice and clean state machine. Has been thoroughly
tested on a Dell Latitude CPiA / NM220 Chip docked to a C/Dock2 with attached
CRT in all possible combinations of LCD/CRT on/off. I changed the config via
Fn key, let the console blank, unblanked by keypress - works flawlessly.
Signed-off-by: Christian Trefzer <ctrefzer@gmx.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
9f672004ab