Re: 2.6 fbcon and 15/16 bpp

[John Zielinski <grim@undead.cc>]

Benjamin Herrenschmidt wrote:

>64 but with only green mattering above 32 iirc, look what XFree does.
>  
>

Good.  I'll make a patch for fbtest then.

>If XFree/fbdev works, then the fbdev is ok :)
>  
>

I'll have to look at the XFree code then to see what they're up to.  
There's a lot of extra dac updates going on that just get overwritten 
again.  If you look at my simulation  you can see that all the updates 
by the second set of OUTREGs gets overwritten by the first set later 
on.    I even disabled the second set in my kernel for 16 bit modes and 
everything still looks the same.   That code is probably there for a 
reason.  I'm just trying to figure out why.  :)

>>PARM: 00    R: 00 (Par:00)  G: 00 (Par:00)  B: 00 (Par:00)  
>>OUT1: 00    R: 00 (Pal:00)  G: 00 (Par:00)  B: 00 (Pal:00)  
>>OUT2: 00    R: 00 (Par:00)  G: 00 (Pal:00)  B: 00 (Par:00)  
>>
>>PARM: 01    R: 01 (Par:01)  G: 01 (Par:01)  B: 01 (Par:01)  
>>OUT1: 04    R: 00 (Pal:00)  G: 01 (Par:01)  B: 00 (Pal:00)  
>>*** Palette green 02 read uninitialized data ***
>>OUT2: 08    R: 01 (Par:01)  G: !! (Pal:02)  B: 01 (Par:01)  
>>
>>PARM: 02    R: 02 (Par:02)  G: 02 (Par:02)  B: 02 (Par:02)  
>>OUT1: 08    R: 01 (Pal:01)  G: 02 (Par:02)  B: 01 (Pal:01)  
>>*** Palette green 04 read uninitialized data ***
>>OUT2: 10    R: 02 (Par:02)  G: !! (Pal:04)  B: 02 (Par:02)  
>>    
>>

As you can see, the dac register 08 is written on the second call by the 
second set of OUTREGs (OUT2:) and then overwritten by the first on the 
third call to the function (OUT1).   It's also grabbing a value for the 
green component from palette array index 2 which hasn't beet updated yet 
(that's what the !! means).  I'm just curious why it's doing this and 
what special case requires it....

John




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