Messages in this thread | | | Date | Mon, 31 Mar 2008 13:21:19 -0400 | From | Mark Lord <> | Subject | Re: 2.6.25-rc7: Ugh. |
| |
Mark Lord wrote: > Mark Lord wrote: >> Oliver Neukum wrote: >>> Am Montag, 31. März 2008 17:04:46 schrieb Mark Lord: >>>> Oliver Neukum wrote: >>>>> Am Montag, 31. März 2008 16:39:33 schrieb Mark Lord: > .. >>>>>> Still want USB_SUSPEND=n ? Please explain. >>>>> It looks like you are hanging in the kthread for autosuspending. >>>>> Compiling that out should confirm it. >>>> .. >>>> >>>> Okay, and once we see that it works fine: then what? >>> >>> We'll combine that information with the result of only removing usbhid >>> and arrive at a pretty good idea where in the kernel the hang occurs. >>> There are only two functions that touch autosuspend in the usbhid code. >>> So if it works with usbhid unloaded, either of them should be to blame. >> .. >> It does still hang with *usbhid* unloaded, >> but not if all USB stuff is unloaded. > .. > > And it does *not* hang with # CONFIG_USB_SUSPEND is not set. > >> I have figured out a way to make this much more reproducible now: >> When suspended, the notebook does not supply +5V over USB. >> But with a voltmeter, I discovered that there is sufficient capacitance >> on the USB +5V, that it takes many minutes for the voltage to decay >> from 5.1V down to near 0V. >> >> Resuming while the voltage is still relatively high, generally works. >> Resuming after the voltage drops to near zero, always fails (with USB >> modules loaded). >> >> So I've put a 2Kohm resistor across the USB +5V lines, >> forcing it to decay to zero within about 5 seconds. >> This helps a lot for debugging here. >> >> It probably also provides a vital clue as to what is wrong. >> Resume seems to generally work when the USB devices maintain >> some amount of standby power, and always fails when they don't. ..
Note that it makes no difference whether I unplug all external USB devices prior to suspend or not. The failure patterns remain the same. -- 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/
| |