>> That could definitely cause mouse lock-ups.  Sorry, that should have
>> occurred to me yesterday when you mentioned the problem your kids
>> were seeing, but it didn't for some reason.
> 
> Btw, could it have caused the USB stack to be *really* confused? Some
> of those mouse lockups ended up also locking the machine hard (ie no
> ping, no nothing), and I'm a bit worried that there was something
> else going on too..   
> 

Unfortunately, yes, that sounds exactly like what happened with the
nVidia controller.  The problem was with my patch, but was fixed with
the later patch.  I doubt there was anything else going on.

> That said, if you can actually re-create the MMF problems, could you
> please try the patch that Arjan suggested? Ie add a 
> 
>       /*
>        * Some broadcom chips are buggy and can't take more than 5 usec
as
> DMA 
>        * latency; inform the rest of kernel of this.
>        */
>       if (weird_broadcom_chip())
>               set_acceptable_latency("ehci", 5);
> 
> to the USB driver, and then add something like
> 
>       static inline int cpufreq_acceptable_latency(struct
cpufreq_policy
>       *policy) {
>               unsigned long latency;
> 
>               /* Policy latency in usec */
>               latency = policy->cpuinfo.transition_latency / 1000;
> 
>               if (latency > system_latency_constraint())
>                       return -EINVAL;
> 
>               return 0;
>       }
> 
> adn then add calls to this from both the "__cpufreq_set_policy()"
> function and the "__cpufreq_driver_target()" one too.. 
> 
> That should disable cpufreq with that broken chip, which is perhaps a
> big draconian, but it's certainly better than having the USB layer
> know about cpufreq internals directly.  
> 
> In the longer run, I think we can move the
> "system_latency_constraint()" 
> checking from the policy registration into each CPU frequency driver,
> so that it could be more dynamically decide about "can we do it right
> _now_"  
> rather than globally saying "we can't do it with this hardware".
> 
>                               Linus

I will work on that, thank you for the help.

Stuart
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