[Intel-gfx] [PATCH 0/2] Automatic 6bpc dither for DisplayPort

[Adam Jackson]

On Mon, 2011-10-10 at 16:33 -0400, Adam Jackson wrote:
> This fixes a rather irritating limitation of active dp->foo converters.
> Many such (including all DP->VGA chips I can find on the market) come
> equipped with only 2 DP lanes, which clips your dotclock to 144MHz at
> 8bpc.  Of the standard DMT modes, that means you lose 1600x1200 at 60 and
> above.  Since these adaptors are marketed as supporting 1920x1200, we
> might as well make that work, otherwise it's the driver that comes
> out looking bad.

After the fix in drm-intel-next to fix the DP bandwidth math this series
is probably less useful, since 1920x1200 will in fact fit in 2x2.7G:

(193250 * 24 + 9) / 10 == 463800

But if you have a Really Very Nice CRT then it might still be desirable.
2048x1536 @ 60Hz GTF for example:

(266950 * 24 + 9) / 10 == 640680
(266950 * 18 + 9) / 10 == 480510

I can respin patch 2 if there's still interest, but it might be
difficult to find a monitor to test against.  Patch 1 is still valid
though.

- ajax