Re: Choosing the correct framebuffer configuration

["Antonino A. Daplas" <adaplas@gmail.com>]

Jon Smirl wrote:
> On 8/7/05, Michel Dänzer <michel@daenzer.net> wrote:
>> On Sun, 2005-08-07 at 18:14 +0200, Benjamin Herrenschmidt wrote:
>>>>> The problem is that the radeonfb driver sees bpp = 32 and then sets
>>>>> rgbt = 8/8/8/8. It stomps rgbt without looking at it.
>>>> Looks like a radeonfb bug.
>>> It's not a bug :) radeonfb doesn't support anything but that format for
>>> now.
>> According to Geert's rules, it should fail instead of rounding down
>> r/g/b.
> 
> One problem with these rules is that it makes it hard to determine
> what is the best config available. I can't just set in 255BPP and then
> let it tell me the best available config.
> 
> What config should I get if everything is zero, BPP and rgbt?
> According to the rules this is an error, should it instead return the
> best config?
> 

Rule is you can round-up but not round-down.

If bpp = 255, error.
If bpp = 0, return the nearest config ie, bpp8, argb8.

Also, drivers look at bpp first. Then it only looks at argb if there are
more than one format per bpp.  That's what most user apps expect.


Tony



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