[Savage40] Image flip

[Young Kim]

Hi, I am not really familar with this forum.
I just copy the body and replying.

Yes, the whole image flips without our own action.
When I say our action, it's not something we do on our own.
I am not so sure if Windows does this or not(I doubt it).
It inverts horizontally and vertically.It's not rotating.
It just happens occasionally.
We can't reproduce it. Our testers have seen couple times.
After sometime, it flips back.


We are developing our own flat panel display which is not standard.
It's resolution is 780x780 and the timing has to be close to 40 hz.
Although the resolution is 780, the backlight is very bright and each
pixel is small(compare to the actual size of the screen), you can't
tell it's low resolution.

Anyway, when we develop our product, we got a partial register spec
from the mother board manufacturer - the chip is integrated. We can't
contact VIA directly since we didn't purchase from VIA. I am just a
software engineer. One of our hardware engineers swore that he read
those registers before. He thinks they are "Horizontal flip" and
"Vertical Flip" - two registers. I think I saw that on other graphics
chips too.

I am pretty sure they are there because we scoped out the LVDS output
stream when it was flipped. The chip is streaming the mirrored image.
Therefore, even O/S(we are using Embedded XP) accepts the mirrored image.
(You know in Windows, the upper left is (0,0) and the lower right is
(780, 780). When it's flipped, the upper left is (780, 780) and lower
right is (0, 0))

If nobody knows, that's fine.
I will look for another way of solving this.

Thanks so much~

-Young


--------------------------------------------------------
Tim Wrote:


Are you talking about the whole image flipping without any action on
your part?  That would be fascinating, because the Savage chips have no
registers to do that.  Indeed, many folks have asked for that feature,
to support notebook computers with displays that swivel.  It does have
the ability to do flipping during a blit operation; there are bits in
the blit command that specify which direction to blit in both X and Y.

What have you set the screen stride to?  That is, how many bytes from
the start of scanline 0 to scanline 1?  Remember that the Savages
require that the frame buffer stride be a multiple of 16 pixels.  That's
why, for example, on a laptop with a 1400x1050 panel, we have to set the
width of the frame buffer at 1408 pixels, even though we only display
the first 1400.  Those last 8 pixels are wasted.

In your case, you probably need to set up the frame buffer for a width
of 800 pixels, although 784 probably works, too.

Why on earth do you need a 780x780 display?

--
Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.