[Savage40] Image flip

[Alex Deucher]

--- Young Kim <buffy.youngkim at gmail.com> wrote:

> 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.
> 

perhaps it's a bug in the windowx XP embedded driver? Or are you
writing the driver yourselves?

> 
> 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.

What are the offsets for the registers you are describing?  Are they
MMIO regs or extended vga?

> 
> 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))
> 

The savages have a crtc base address swapping control that allows you
to swap the buffer from which the crtc reads, perhaps that's not being
set properly? still, I don't see how that create a mirror image.

Alex

> 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.
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> Savage40 at probo.com
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> 


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