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[directfb-users] Re: WAITFORSYNC sleeps too long
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[directfb-users] Re: WAITFORSYNC sleeps too long



Hi Ville,

first of all thank you for your quick and comprehensive reply. :)
I'm forwarding this to my colleagues so hopefully we'll see clearer by
tomorrow.

> > Why does the wait_event_bla fail? Isn't there any VSYNC interrupt? How
> > can this happen? 
> 
> Obviously the first thing to check is if your kernel actually supports 
> FBIO_WAITFORSYNC ioctl.

Are there any 2.6 kernels that don't support it? How can we check this?
Probably by looking at the sources?

> 
> Secondly make sure the graphics card actually has an irq assigned to it. 
> BIOS usually has an option for it. lspci should tell you if the irq is 
> assigned.
> 
> If everything checks out the next step would probably adding some debug 
> printks to the kernel to see what happens. One thing that might be the 
> cause is some irq routing problem (ACPI related maybe).

That means switching ACPI off could help?


> > I've got no idea of where this interrupt should normally come from, but
> > could this be caused by a second PCI graphics board in the machine, on
> > which an Xserver runs?
> 
> I doubt that should cause any problems unless the Xserver is told 
> to touch the G550. Or maybe the Xserver is stupid an pokes at some 
> VGA ports while shouldn't. Which card is inited by the BIOS?

I guess it's the PCI card, but I'll check this.

> If someone actually disables the interrupt you should see a message from 
> matroxfb with dmesg.

ok, we'll see.

Thanks,
Jan





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