Messages in this thread | | | Subject | Re: 2.4.22 USB problem (uhci) | From | Jan Rychter <> | Date | Fri, 19 Sep 2003 14:14:49 -0700 |
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>>>>> "Greg" == Greg KH <greg@kroah.com> writes: Greg> On Fri, Sep 19, 2003 at 01:29:55PM -0700, Jan Rychter wrote: If Greg> you want to suspend using 2.4, unload the usb drivers entirely. Greg> That's the only safe way. >> >> I wasn't talking about suspending, but about processor >> C-states. These are power states that the mobile processors enter >> dynamically, many times a second. In my case:
Greg> Ah, sorry. I'm getting D and C states mixed up here. [...]
You probably mean S-states, which are for sleep.
>> As you can see, C3 (lowest power) is being used a lot. This makes my >> laptop run cool. If I use usb-uhci, the processor is never able to >> go into C3 because of DMA activity. uhci is better, because it at >> least permits me to use C3 when there are no devices plugged in. >> >> And going back to the uhci problem... ?
Greg> UHCI by design sucks massive PCI bandwidth. There is logic in Greg> the uhci drivers that try to help this out by reducing Greg> transactions when not much is going on, but there's only so much Greg> we can do in software, sorry. I'm guessing that you aren't going Greg> to be able to change this.
Greg> Unless you go buy a ohci usb cardbus controller card :)
Now you've confused me.
Do your comments above apply to "uhci" or "usb-uhci"?
Please allow me to restate the original problem:
-- I usually use uhci instead of usb-uhci, because it is able to go into "suspend mode" when no devices are plugged, which allows the CPU to enter C3 states,
-- usb-uhci eats CPU power by keeping it in C2 constantly because of busmastering DMA activity, therefore being much less useful,
-- uhci generally works for me just fine, but breaks in one particular case, when removing the device causes a strange message to be printed and the system being unable to use the C3 states again, until uhci is unloaded and reloaded back again.
Just as a reminder, this message is:
uhci.c: efe0: host controller halted. very bad
I hope if the message says "very bad", then this is something that can be fixed. I was therefore reporting a problem with "uhci" and kindly asking for help.
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