LCM flicker

[Andy Green]

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Somebody in the thread at some point said:
> On Mon, 10 Mar 2008 08:27:23 +0000 Andy Green <andy at openmoko.com> babbled:
> 
> Somebody in the thread at some point said:
> 
>>>> one thing it could be is the LSB of all channels is wobbling, and since R &
>>>> B have 1 less bit - it's much more noticable. green might flicker and we
>>>> just
> Good idea Carsten -- and in fact the physical interface to the LCM is
> 6:6:6 fittingly enough, and that is what is wired through to the Glamo.
>  But glamo framebuffer in U-Boot anyway (X too?) is 5:6:5 and it is
> *red* and *blue* that lack the LSB.
> 
>> well 6bits is what the lcd accepts (6:6:6 indeed) and the glamo needs to fill
>> in the extra 1 bit for R & G (G goes straight through as all 6 bits are used).
>> that extra 1 bit needs to be interpolated from 0 to 1 as the other 5 bits
>> increase in value. but flicker ONLY happens when R != B.  and it gets worse the
>> more difference between R & B. now if those lines are flapping and not grounded

Floating signals are generally a lot less controlled than this regular
flicker though.  We would see artifacts when someone turned on the
lights or pulled out a plug in another room.

The structure seems to be that the 5:6:5 goes through individual gamma
tables in the Glamo and that is where the extra LSB is picked up.  I'll
start looking there.

I looked at the Glamo LCD controller "Enable and Mode Setting Register
3" at +1104 and we are set for RGB 5:6:5 on the CPU side, RGB (not
"LCD?") 6:6:6 on the LCD side and 18 bit if, so it is alright as far as
that goes.

- -Andy
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