Re: [PATCH 2/2] cirrusfb: use 24bpp instead of 32bpp

Re: [PATCH 2/2] cirrusfb: use 24bpp instead of 32bpp

[Ondrej Zajicek]

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On Fri, Feb 27, 2009 at 09:48:53PM +0100, Krzysztof Helt wrote:
> From: Krzysztof Helt <krzysztof.h1@wp.pl>
> 
> The 32bpp is supported only on the latest
> Cirrus Logic chips. Use the 24bpp which
> is supported at least since Alpine chips
> (GD543x).
> 
> Change 32bpp mode setting to 24bpp mode.

Why do not support both modes?

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago@crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."

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Re: [PATCH 2/2] cirrusfb: use 24bpp instead of 32bpp

[Krzysztof Helt]

On Fri, 27 Feb 2009 23:30:31 +0100
Ondrej Zajicek <santiago@crfreenet.org> wrote:

> On Fri, Feb 27, 2009 at 09:48:53PM +0100, Krzysztof Helt wrote:
> > From: Krzysztof Helt <krzysztof.h1@wp.pl>
> > 
> > The 32bpp is supported only on the latest
> > Cirrus Logic chips. Use the 24bpp which
> > is supported at least since Alpine chips
> > (GD543x).
> > 
> > Change 32bpp mode setting to 24bpp mode.
> 
> Why do not support both modes?
> 

1. The 32bpp is broken or unsupported on all chips except Laguna ones (on Laguna I made it work a week or two ago).
2. Very little to gain from 32-bit (is the alpha channel used on fb?). The previous implementation just set transparency to 0
length.
3. It is supported only on Laguna and GD5480 (and I have only one Laguna chip to test). It should work on GD5436/46 but it does not (even X11 driver left it out).
4. Acceleration for GD5480 would be untested in 32-bit mode (Laguna has no acceleration anyway) - probably (surely) broken.

Regards,
Krzysztof

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