On Fri, 29 Jul 2005, Antonino A. Daplas wrote: > Jon Smirl wrote: > > On 7/28/05, Geert Uytterhoeven <[EMAIL PROTECTED]> 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.
Indeed. One bits_per_color cannot handle e.g. RGB565 (or RGBA{10,10,10,2} :-). > > If that isn't good enough I can switch the attribute to take strings > > like ARGB8888. > > > > Please no. Ack. > > 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. Yes it has, but since binary data is more compact, you can fit more data in PAGE_SIZE. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [EMAIL PROTECTED] In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/