Output order on Radeon X1950 [patch]

Jörg Walter jwalt at garni.ch
Wed Oct 22 05:33:59 PDT 2008

On Wednesday, 22. October 2008, Michel Dänzer wrote:
> > Still, all other drivers, including Windows, agree on "first" vs.
> > "second" output connector, regardless of RandR 1.2 or not -- point is, if
> > I switch drivers or OS, my primary display suddenly isn't primary
> > anymore, kdm appears on the wrong screen, as does the taskbar or yakuake.
> The thing is, I don't think RandR 1.2 defines a 'primary' CRTC/output at
> all. It sounds like things should be fine if clients remembered things
> from the names or geometry of outputs rather than their arbitrary
> enumeration order.

Well, RandR defines an order. It's the order the "xrandr" utility shows.

Semantically, order may not be considered significant. In practice, a defined 
(but implementation-dependent) order exists and will be used for default 
settings all over the place. Providing sane defaults that agree with everyone 
else are IMHO worth quite a bit, especially since current software doesn't 
allow connector-name based configuration.

Given that RandR 1.2 has the notion of a "compat" output (see 
hw/xfree86/doc/README.modes), one connector actually does have special 
semantics. It is a kind of 'primary' output for all X extensions that are 
unaware of RandR 1.2 (e.g., XVidMode).

I agree that name-based settings make a lot of sense in the long run. Hence, 
my patch doesn't change the names, just the order in which they are 
registered. Current software, however, just honours the order in which screens 
are returned by RandR (or Xinerama, in the case of fglrx). And even with name-
aware software, default settings will still be based on the order, and so 
radeon will behave opposite to everyone else by default, for no benefit.

BTW, the two RandR-1.2 compatible drivers radeon and radeonhd disagree on 
names as well: "DVI-1" vs. "DVI-I_2/analog" for the second connector. Who 
knows what fglrx will bring... I don't care a lot about the exact naming 
scheme, and when software begins to remember screens by name, it hopefully can 
remember multiple "preferred" screens in order to cope with different naming 


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