Re: [Linux-fbdev-devel] Supporting various depth

[Romain D. <do...@ir...>]

Geert Uytterhoeven wrote:

> No, -depth actually means bits-per-pixel in fbset (yes this is a bug).

Are those details documented anywhere ? That would make life easier
for you not to have to answer questions on fbset all the time :-)

I'm about to add the following blurb to the pm3fb home page to
explain details, so 1) did I understand fbset correctly 2) is
it understandable ? (the pm3fb part is a little optimistic
as the code isn't finished yet ;-)

TIA

####
Depth, BitsPerPixel and fbset

There's a little bit of confusion on the proper use of some terms
in this page and in the fbset software. 

 + Depth should be the actual number of bits used
   for the color of the pixel (above, significants bits) 
 + BitsPerPixel should be the actual number of bits used
   in the memory of the framebuffer per pixel, regardless of depth. 

Unfortunately, fbset -depth X should really be fbset -bpp X as it
means 'set the framebuffer to that number of bits per pixels in
memory, or more'. For TrueColor mode, there's an option -rgba R,G,B,A
to give the number of significant bits for each color component. So to
get Depth 15 in 16 BitsPerPixels, i.e 5 bits for each of red, green
and blue plus a spare bit, one should use: fbset -depth 16 -rgba
5,5,5,1.

At the moment, if you use fbset -depth 15, pm3fb will also use RGB 5551
and 16bpp but I'm not sure it's the right behavior. fbset -depth 16 will
default to RGB 565.
#####


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DOLBEAU Romain               | l'histoire est entierement vraie, puisque
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