Messages in this thread | | | Date | Fri, 29 Jul 2005 06:28:21 +0800 | Subject | Re: [Linux-fbdev-devel] Re: [PATCH] fbdev: colormap fixes | From | "Antonino A. Daplas" <> |
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Jon Smirl wrote: > On 7/28/05, Geert Uytterhoeven <geert@linux-m68k.org> wrote: >> On Thu, 28 Jul 2005, Jon Smirl wrote: >>> I've verified now that all ATI R300+ chips have 10bit cmaps. These are >>> pretty common so I'd be in favor of making this into a binary >>> attribute where I can get/set the whole table at once. Given that >>> OpenGL is already supporting 12 and 16 bits these tables are only >>> going to get much larger. >>> >>> 1024 entries * 5 fields * 2 bytes = 10KB -- too big for a text attribute. >>> >>> 65536 entries * 5 fields * 2 bytes = 655KB -- way too big for a text attribute. >>> >>> The bits_per_pixel sysfs attribute is an easy way to tell how many >>> entries you need. You can just set it at 4, 8, 10, etc until you get >>> an error. Now you know the max. 2^n and you know how many entries. >> No, bits_per_pixel can be (much) larger than the color map size. E.g. a simple >> ARGB8888 directcolor mode has bits_per_pixel = 32 and color map size = 256. > > So I have the bits_per_pixel attribute wrong in sysfs. It needs to be > bits_per_color and then let the driver sort it out. Otherwise there > is no way to set ARGB8888 versus ARGB2101010. With bits per color you > would set 8 or 10. >
No, you have to add another attribute for {transp|red|green|blue}.{len,offset} and another attribute for the pixelformat. Then using those, one can easily deduce the cmap size. > If that isn't good enough I can switch the attribute to take strings > like ARGB8888. >
Please no.
> What do you think, should I just switch to fbconfig names and a binary > cmap attribute? >
Does a binary attribute not have the same buffer size limitation as the text attribute? I really don't know, just asking.
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