Re: [PATCH] pxafb: Add support for other palette formats

[Paulo Marques <pmarques@grupopie.com>]

Hans-Jürgen Koch wrote:
> Am Dienstag 03 Juli 2007 18:03 schrieb Paulo Marques:
>> [...]
>> Or maybe teach fbcon to use 18bpp modes?
> 
> This would only make sense if this is a common format that other
> chips use, too.

I don't see this as a good reason not to implement 18bpp support in 
fbcon. "Just PXA270 18bpp devices" can be a lot of devices out there.

Anyway, can fbcon work with 18bpp palette mode? If it does, then this 
should be enough for most users of 18bpp pxafb users: have a console 
with a palette mode and then switch to non-palette mode and run whatever 
windowing system supports 18bpp.

I guess that even if it doesn't support 18bpp palette mode now, it 
shouldn't be that hard to implement (nor should it cause that much bloat 
to fbcon).

>>> BTW: PXA255 doesn't have an LCCR4 register.
>> If we make sure that we don't touch LCCR4 registers unless the platform 
>> driver asks for 18bpp we should be in the clear, no?
>>
>> However, the current patch does write to LCCR4 without checking this, 
>> but this should be a no-op if there is no register there, AFAICS.
> 
> Arrg, no, you can't do this. Even if it works on your current PXA255
> revision, writing to a nonexistent register is certainly not something
> we should do in a proper driver.

Yes, I wasn't proposing that this be kept (that would be waaay too 
ugly), only pointing out that it shouldn't crash existing setups.

>> I'll try to handle it more correctly in my next patch, anyway.
> 
> So will I. I'll update my patch.

Ok.

-- 
Paulo Marques - www.grupopie.com

"God is real, unless declared integer."

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