radeon, M22 X300, a pair of monitors, and maximizing resolution with good performance

[Alex Deucher]

On Fri, Mar 28, 2008 at 5:39 PM, Thomas Vaughan <tevaughan at gmail.com> wrote:
> On Fri, Mar 28, 2008 at 9:57 AM, Alex Deucher <alexdeucher at gmail.com>
>  wrote:
>  >
>  > On Fri, Mar 28, 2008 at 9:32 AM, Thomas Vaughan <tevaughan at gmail.com>
>  > wrote:
>  > >
>  > > Just to be clear---in case anyone might be confused by my sloppy
>  > > wording---I rotated clockwise each of the two 1600x1200 LCD panels
>  > > attached to my docking station.  Then I used 'Option "Rotate"
>  > > "Left"' on each of them.  With side-by-side monitors, each in
>  > > portrait orientation (instead of the usual landscape orientation),
>  > > my virtual desktop size was then 2400x1600.
>  >
>  > accelerated rotation uses textures to rotate the desktop, so the max
>  > size would be 2048x2048.
>
>  But for rotation of a monitor, one doesn't want to rotate the whole
>  desktop.  One wishes only to rotate for each monitor the portion of the
>  display that appears on that monitor.  In my case, it would seem that I
>  need two textures, each 1600x1200.
>

that would be true if it worked that way :)  The way randr 1.2 works
is that a single large surface is allocated for the entire desktop and
each crtc scans out of a portion of that desktop.  For rotation the we
use a rotated buffer of the same size.

>  > Option "AccelMethod" "EXA"
>
>  Thanks!
>
>  > > > On second thought, I'm afraid this won't help as the 3D engine
>  > > > probably only supports textures up to 2048x2048.
>  > >
>  > > Well, that would matter (hopefully) only if I actually wanted to use
>  > > textures bigger than 2048x2048.  Perhaps it would affect me if I
>  > > wanted to use a big texture for the whole virtual desktop.
>  >
>  > When using accelerated rotation with EXA, textures are used so the
>  > limit applies here.
>
>  Again, I'm not seeing why EXA would need a single texture for the entire
>  virtual desktop.  It would seem to need a texture for each 1600x1200
>  monitor.

In order to work properly with the DRI, FB layer, XAA, etc. we
implemented xrandr using a single large surface.  It's not optimal,
but with exa and ttm, we'll be able to move to a better implementation
eventually.

Alex