Re: ukbd: short freeze when activating LEDs

On Saturday 05 September 2009 18:02:37 you wrote:
> On Saturday 05 September 2009 16:32:55 Stefan Ehmann wrote:
> > Whenever I press capslock/numlock, the system shortly (< 0.5 ms) freezes.
> 
> How did you measure this?
The mouse is not responding and sound also stops during that period.
It's probably much shorter, more likely 0.1-0.2ms. 

> Are you able to figure out why it is hanging?
> 
> Has this got anything to do with BIOS or microcode running on the CPU?
No idea. top shows > 95% interrupt if I'm on the console, in xorg the cpu goes 
to system. Interestingly, the number of interrupts displayed by systat is very 
moderate (if I just move the mouse, it's much higher)

> USB keyboard LEDs are set asynchronously. It should not block like you
> explain.

The keyboard works fine on my notebook. I think the problem is the USB 
controller on my PC, not the keyboard driver. dmesg reports it as
uhci0: <VIA 83C572 USB controller> port 0xb400-0xb41f at device 16.0 on pci0
uhci0: [ITHREAD]
uhci0: LegSup = 0x003a
usbus0: <VIA 83C572 USB controller> on uhci0

Historically, I've always had lots of trouble with USB on this particular PC.
With the old USB code, I've got lots of issues. scanner didn't work at all, 
sometimes even problems with basic things like umass.

With new USB things are much better, but not always perfect.

If there's no easy way to debug, it's probably not worth the hassle. The PC is 
nearing the end of its life-time anyway.

-- 
Thanks,
Stefan