Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] PCI / tg3: Give up chip reset and carrier loss handling if PCI device is not present | Date | Mon, 02 Dec 2013 02:18:50 +0100 |
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On Sunday, December 01, 2013 12:39:19 PM Michael Chan wrote: > On Sun, 2013-12-01 at 02:34 +0100, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > Modify tg3_chip_reset() and tg3_close() to check if the PCI network > > adapter device is accessible at all in order to skip poking it or > > trying to handle a carrier loss in vain when that's not the case. > > Introduce a special PCI helper function pci_device_is_present() > > for this purpose. > > > > Of course, this uncovers the lack of the appropriate RTNL locking > > in tg3_suspend() and tg3_resume(), so add that locking in there > > too. > > > > These changes prevent tg3 from burning a CPU at 100% load level for > > solid several seconds after the Thunderbolt link is disconnected from > > a Matrox DS1 docking station. > > I'm not familiar with the DS1. Does the tg3 device get removed through > tg3_remove_one() in this case?
Yes, this is a normal removal except that the device is gone physically when it happens.
Thunderbolt cable disconnect is like a power failure for all devices on the link (that is, all devices in the DS1 in this particular case).
> What happens when you reconnect the DS1?
Well, it works. ACPIPHP just waits for the removal to complete and then it handles the hot-add event and the device works normally after that.
The only problem is that without the patch the hot-removal takes a few seconds and quite a lot of CPU power due to the tight loop spinning in tg3_carrier_off() called by tg3_close(), while with the patch it just happens almost instantaneously.
And in the Thunderbolt disconnect case doing the entire tg3_chip_reset() is pointless anyway, because the config space of the device is not available then.
Thanks!
-- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.
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