xorg-server-dummy: cannot add additional xrandr mode (xrandr: Configure crtc 0 failed)

[Nicolas Boichat]

Hi all,

I investigated a bit more with gdb, and I noticed that the error
happens at randr/rrcrtc.c:519:
RRCrtcSet fails at ret = (*pScrPriv->rrCrtcSet) (pScreen, crtc, mode, x, y,
                                         rotation, numOutputs, outputs);
This calls xf86RandRSetConfig in hw/xfree86/common/xf86RandR.c, but
the new mode is not in scrp->modes.

Does the driver need to do something special to add new custom modes
to scrp->modes?

Any pointer would be greatly appreciated...

Thanks,

Nicolas

On Fri, Sep 19, 2014 at 4:18 PM, Nicolas Boichat <drinkcat at chromium.org> wrote:
> Hi,
>
> I'm running a dummy X11 server (Xorg 1.15.1 on Ubuntu 14.04), using
> the configuration attached.
>
> I am able to change resolution using xrandr, as long as I use the ones
> that are setup when the server is started (either the default ones, or
> the ones I add in the Monitor section).
>
> I'd like to be able to add new arbitrary resolutions using output from
> gtf, but this fails:
> # xrandr --newmode 800x632_60.00 40.24 800 832 912 1024 632 633 636
> 655 -HSync +Vsync
> # xrandr --addmode default 800x632_60.00
> xrandr: Failed to get size of gamma for output default
> (I guess this is harmless: the mode is added)
> # xrandr --output default --mode 800x632_60.00 --verbose
> xrandr: Failed to get size of gamma for output default
> crtc 0: disable
> screen 0: 800x632 211x167 mm  96.09dpi
> crtc 0: 800x632_60.00   60.0 +0+0 "default"
> xrandr: Configure crtc 0 failed
> crtc 0: disable
> screen 0: revert
> crtc 0: revert
>
> A similar method works fine with intel drivers.
>
> Any idea if this is supposed to work, or if I am doing something
> wrong? Or is this something that the dummy driver does not support?
>
> Thanks a lot for your help,
>
> Best regards,
>
> Nicolas