Sprite transforms in RandR

Daniel Stone daniel at fooishbar.org
Mon Dec 6 10:20:00 PST 2010


On Mon, Dec 06, 2010 at 10:07:40AM -0800, Keith Packard wrote:
> On Mon, 6 Dec 2010 09:42:24 -0800, Aaron Plattner <aplattner at nvidia.com> wrote:
> > Are there really no dumb little phones or something that can rotate the
> > internal screen but not external displays?  I'd feel more comfortable if
> > someone familiar with the various embedded graphics chips would chime in
> > with an ack/nack.
> That's why I asked Daniel -- he was dealing with a phone that had
> hardware rotation support (some OMAP thing), and he says that the
> hardware will rotate on any CRTC (it's got TV out).

Yep.  OMAP has no per-output limitations across LCD/TMDS/TV/external
LCD, to a point.  I can't speak for Qualcomm (although xf86-video-msm
just calls straight down to fbdev for modesetting, with one CRTC),
Freescale, Samsung, etc, though.

> > I guess outputs have a mask of allowable rotations provided to the clients.
> > Maybe that's sufficient: you can only use hardware rotation if the
> > scanoutpixmapinfo *and* the corresponding output rotation mask say you can,
> > and otherwise you get to do the rotation yourself with the graphics
> > hardware?
> Right. The question is only whether separate outputs need *different*
> scanout pixmap formats.

Not TTBOMK.  I can imagine a case where TV-out might require a different
set of formats to the rest of the display block, but I've also yet to
see it.

> > One thing that reminded me of is how the requested rotation is going to be
> > communicated to the compositor.  Should we add something like a
> > RRConfigRedirectMask, or will the clients be expected to invent their own
> > new protocol for sending configuration requests to the compositor?
> I wonder how it works today; I've got a phone that appears to allow
> applications to rotate the screen, do they actually have applications
> doing the RandR calls?

Depends which phone it is. :) For the N900, there's a 'rotate me please'
window property; if conditions are right, then the compositor will
initiate rotation when that window is in the foreground.  (There's also
a hack to rotate the input devices to match the outputs, which I should
redo properly at some point ...)

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