On 17 Jan 01 at 12:11, James Simmons wrote:
> Okay. This answered my previous question. It pretty much comes down to
> choosing between xxxfb_setcolreg or xxxfb_set_cmap. Their are pros and
> cons to having each:
>
> xxxfb_setcolreg
> PRO: can change a individual register without having to monkey
> with the entire CLUT.
>
> CONS: Hardware designs. Some hardware require vsync when changing
> the color palette.
>
> xxxfb_set_cmap
> PRO: More flexiable with bizarre hardware. Also works nice with
> hardware that has more than one CLUT. In this case we can
> cache a bunch of color maps and switch the index around.
>
> CONS: Can't change a subset of teh CLUT table easily.
Adding 'CMAP_FIRST' and 'CMAP_MORE' bits as additional setcolreg
argument? And set CMAP_FIRST for first entry of cmap, and CMAP_MORE
if it is not last entry? So VGA could do:
if (flags & CMAP_FIRST) {
outb(reg, 0x3C8);
}
outb(red, 0x3C9);
outb(green, 0x3C9);
outb(blue, 0x3C9);
I have no idea whether someone really needs CMAP_MORE. Maybe if you
must enable legacy VGA I/O region for doing palette changes... Or if
you must switch DAC back to 6bit mode for legacy apps.
Best regards,
Petr Vandrovec
van...@vc...
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