Re: [E1000-devel] e1000e interface hang on 82574L

From: Bjorn Helgaas <bhelgaas@google.com>
To: Chris Boot <bootc@bootc.net>
Cc: Nix <nix@esperi.org.uk>,
	"Wyborny, Carolyn" <carolyn.wyborny@intel.com>,
	e1000-devel@lists.sourceforge.net,
	netdev <netdev@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	linux-pci@vger.kernel.org, Matthew Garrett <mjg@redhat.com>
Subject: Re: [E1000-devel] e1000e interface hang on 82574L
Date: Fri, 6 Apr 2012 06:12:58 -0600	[thread overview]
Message-ID: <CAErSpo4TJ-9NsD5QTpFi9fsnD9qHt7+Tr5jJHQPuS7vg6ghq_w@mail.gmail.com> (raw)
In-Reply-To: <1590F833-7D40-42FE-8FA2-6DCCADF9C6B0@bootc.net>

On Fri, Apr 6, 2012 at 4:17 AM, Chris Boot <bootc@bootc.net> wrote:
> On 19 Mar 2012, at 17:31, Nix wrote:
>
>> On 19 Mar 2012, Carolyn Wyborny said:
>>
>>>> you'll see that I tested that, and it doesn't work :( even if it did
>>>> work, it shouldn't be needed: the driver attempts to turn off PCIe ASPM
>>>> on affected NICs, and fails, apparently because *something* turns it
>>>> back on again.
>>>>
>>> The driver attempts to disable L0s state, not the entire feature. It
>>
>> It tries to disable L1 state as well (or it did when I tested this last,
>> although I suspect you're right and it may leave L1 turned on these
>> days: judging by the contents of e1000_82574_info, anyway.)
>>
>>> is also required that the device upstream on the bus from the 82574L
>>> have this disabled. Yes, I agree there appears to be something in the
>>> os that either ren-enables or fails to disable the feature on the
>>> upstream device, as desired. Platforms/systems also appear to vary in
>>> this regard, so the solutions may vary a bit as well.
>>>
>>> Its worth trying your solution as well if what I suggested doesn't
>>> work, but there is not one solution that fits all, unfortunately.
>>
>> I don't *have* a solution. :( 'setpci by hand some unknown amount of
>> time after booting once the interface has stabilized' hardly counts as a
>> solution of any sort. It's, at best, a workaround that lets me use my
>> systems without hourly lockups until a real solution is found.
>>
>> (To clarify: manual setpci to force off the ASPM bits is the only thing
>> that works for me. The driver's automatic disabling of L0s and L1
>> doesn't work: nor does booting with pcie_aspm=off. In both cases, I end
>> up with both L0s and L1 turned on, and a lockup some time later, unless
>> I setpci the bits off by hand.)
>
>
> Well, with that setpci incantation run against the NIC and its upstream device to disable ASPM L1s (setpci -s <dev> CAP_EXP+10.b=40), everything has been working very well indeed. Is there something the e1000e driver could do to disable L1s as well as L0s if we know there's a problem with them for these devices?
>
> Adding Bjorn Helgaas and linux-pci to CCs to try to get the ball rolling some more, as this is crippling without the fixes.

[+cc Matthew Garrett for ASPM stuff]

If I understand correctly, e1000e attempts to disable ASPM to work
around an 82574L hardware erratum, but the PCI core either doesn't
disable ASPM or it gets re-enabled somehow.