Interrupt stom on cardbus device

[Robert Noland]

On Sun, 2009-03-01 at 01:15 -0800, Jakub Lach wrote:
> Hello.
> 
> I also had such problems with interrupt storm @ IRQ 16. Hardware is Lenovo
> T400 (X4500,GM45) Patch greatly helped, although it  introduces other
> problem. As long as output from glxgears is at ttyv0, it is working fine. I
> output is @ xterm window, it stutters while writing the FPS count. If output
> is at ttyv0 and I switch terminal from X11 to ttyv0 while glxgears is
> working glxgears stutters too. 

Ok, I can try to look into this at some point, but right now it is not
high priority.  When you VT switch, the irq handler gets uninstalled,
and the vblank counters get reset in hardware.  We attempt to deal with
that case, but it's not optimal.  As for stutter when printing while in
X, it could be text rendering performance ( which kinda sucks right now,
at least on intel ), it could also be that the G45 handles vblank
counters differently.

But I'm glad that the patch resolved the interrupt storm.  It's likely
that it will help other devices than graphics cards as well...

robert.

> dmesg
> 
> drm0: <Mobile IntelÂŽ GM45 Express Chipset> on vgapci0
> info: [drm] MSI enabled 1 message(s)
> vgapci0: child drm0 requested pci_enable_busmaster
> info: [drm] AGP at 0xd0000000 256MB
> info: [drm] Initialized i915 1.6.0 20080730
> drm0: [ITHREAD]
> error: [drm:pid26643:gm45_get_vblank_counter] *ERROR* trying to get vblank
> count for disabled pipe 0
> drm0: [ITHREAD]
> drm0: [ITHREAD]
> drm0: [ITHREAD]
> 
> best regards, 
> Jakub Lach
-- 
Robert Noland <rnoland at FreeBSD.org>
FreeBSD
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