accessing legacy(?) VGA input status register 1 on 945GM/xf86-video-intel

Michel Dänzer michel at
Fri Sep 26 07:30:31 PDT 2008

On Fri, 2008-09-26 at 16:05 +0200, René Rebe wrote:
> Theo Veenker wrote:
> > Jesse Barnes wrote:
> >>
> >> There's some code in the xf86-video-intel driver to disable vblank interrupts 
> >> when no 3D client is running (look for want_vblank_interrupts in i830_dri.c, 
> >> you can either remove the code from I830DRISetVBlankInterrupt or make that 
> >> field unconditionally true).  Maybe that's what you already did.
> >>     
> >
> > Yes that's what I did. With the stock driver drm vblank would only work while
> > running, for instance, glxgears. After the 'fix' I just need to run glxgears
> > once and after that it works. I can live with that.
> >   
> You do not "fix" it, but mangle a power saving feature not to wake the CPU
> while vblank is not wanted by any client.

That 'feature' is broken by design and will be superseded by the DRM

Earthling Michel Dänzer           |
Libre software enthusiast         |          Debian, X and DRI developer

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