Messages in this thread | | | Date | Fri, 19 Sep 2003 14:22:32 -0700 | From | Greg KH <> | Subject | Re: 2.4.22 USB problem (uhci) |
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On Fri, Sep 19, 2003 at 02:14:49PM -0700, Jan Rychter wrote: > >>>>> "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.
Ugh, ok, I give up :)
> >> 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.
Ok, sorry for the confusion. No I don't know of a fix for this problem, but one just went into the 2.6 kernel tree for the uhci-hcd driver that you might want to take a look at that fixed a problem almost exactly like this.
thanks,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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