On Wed, 13 Jul 2011 16:32:32 -0400, Adam Jackson <a...@redhat.com> wrote:
> Consider a 1600x900 panel, upscaling a 1360x768 mode, full-aspect. The
> old math would give you:
>
> scaled_width = 1600 * 768; /* 1228800 */
> scaled_height = 1360 * 900; /* 1224000 */
> if (scaled_width > scaled_height) { /* pillarbox, and true */
> width = 1224000 / 768; /* int(1593.75) = 1593 */
> x = (1600 - 1593 + 1) / 2; /* 4 */
> y = 0;
> height = 768;
> } /* ... */
>
> This is broken. The total width of scanout would then be 1593 + 4 + 4,
> or 1601, which is wider than the panel itself. The hardware very
> dutifully implements this, and you end up with a black 45° diagonal from
> the top-left corner to the bottom edge of the screen. It's a cool
> effect and all, but not what you wanted. Similar things happen for the
> letterbox case.
I'm going to show my ignorance but why did the hw apply the offset to both
sides of the output and generate a new mode line? That's probably inherent
in the nature of the hblanks, I guess? The entirety of the description I
have is that the position is simply the origin of the top-left pixel of the
fitted window.
So a comment here is necessary, but otherwise:
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38851
Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>
And a big thank you.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
