Message-ID: <4d2084e5-abec-b046-a304-8ca7db4c269f@gmail.com>
Date:   Tue, 18 Dec 2018 19:21:54 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Chris Chiu <chiu@...lessm.com>
Cc:     nic_swsd <nic_swsd@...ltek.com>, davem@...emloft.net,
        netdev@...r.kernel.org,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Linux Upstreaming Team <linux@...lessm.com>
Subject: Re: A weird problem of Realtek r8168 after resume from S3

On 18.12.2018 14:25, Chris Chiu wrote:
> On Tue, Dec 18, 2018 at 3:08 AM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>
>> On 17.12.2018 14:25, Chris Chiu wrote:
>>> On Fri, Dec 14, 2018 at 3:37 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>>>
>>>> On 14.12.2018 04:33, Chris Chiu wrote:
>>>>> On Thu, Dec 13, 2018 at 10:20 AM Chris Chiu <chiu@...lessm.com> wrote:
>>>>>>
>>>>>> Hi,
>>>>>>     We got an acer laptop which has a problem with ethernet networking after
>>>>>> resuming from S3. The ethernet is popular realtek r8168. The lspci shows as
>>>>>> follows.
>>>>>> 02:00.1 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd.
>>>>>> RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 12)
>>>>>>
>>>> Helpful would be a "dmesg | grep r8169", especially chip name + XID.
>>>>
>>> [   22.362774] r8169 0000:02:00.1 (unnamed net_device)
>>> (uninitialized): mac_version = 0x2b
>>> [   22.365580] libphy: r8169: probed
>>> [   22.365958] r8169 0000:02:00.1 eth0: RTL8411, 00:e0:b8:1f:cb:83,
>>> XID 5c800800, IRQ 38
>>> [   22.365961] r8169 0000:02:00.1 eth0: jumbo features [frames: 9200
>>> bytes, tx checksumming: ko]
>>>
>> Thanks for the info.
>>
>>>>>>     The problem is the ethernet is not accessible after resume. Pinging via
>>>>>> ethernet always shows the response `Destination Host Unreachable`. However,
>>>>>> the interesting part is, when I run tcpdump to monitor the problematic ethernet
>>>>>> interface, the networking is back to alive. But it's dead again after
>>>>>> I stop tcpdump.
>>>>>> One more thing, if I ping the problematic machine from others, it achieves the
>>>>>> same effect as above tcpdump. Maybe it's about the register setting for RX path?
>>>>>>
>>>> You could compare the register dumps (ethtool -d) before and after S3 sleep
>>>> to find out whether there's a difference.
>>>>
>>>
>>> Actually, I just found I lead the wrong direction. The S3 suspend does
>>> help to reproduce,
>>> but it's not necessary. All I need to do is ping around 5 mins and the
>>> network connection
>>> fails.  And I also find one thing interesting, disabling the  MSI-X
>>> interrupt like commit
>>> [d49c88d7677ba737e9d2759a87db0402d5ab2607] can fix this problem.
>>> Although I don't
>>> understand the root cause. Anything I can do to help?
>>>
>> This is indeed very, very weird. You say switching from MSI-X to MSI fixes
>> the issue, but also pinging the machine from outside brings back the network.
>> Both actions affect totally different corners.
>>
>> The commit and related issue you mention was a workaround in the driver,
>> the root cause was a MSI-X-related  issue with certain Intel chipsets deep
>> in the PCI core. After this was fixed we removed the workaround again.
>> This shouldn't be related to your issue.
>>
>> Hard to say for now is whether the issue is:
>> - a driver issue
>> - a hardware issue in the RTL8411
>> - an issue with the chipset on your mainboard
>>
>> According to your description it doesn't take a special scenario to trigger
>> the issue, so most likely also other users of Acer notebooks with RTL8411
>> should be affected (after briefly checking this should be at least Aspire
>> F15, V15, V7). Therefore I wonder why there aren't more reports.
>>
>> This commit added MSI-X support: 6c6aa15fdea5 ("r8169: improve interrupt handling")
>> So you could test this revision and the one before.
>>
>> Eventually, if the issue really should be caused by a side effect of using
>> MSI-X, then the question is whether we need to disable MSI-X for RTL8411
>> in general or just for RTL8411 and a certain subsystem id.
>>
> 
> I tried the kernel with the head on 6c6aa15fdea5 ("r8169: improve
> interrupt handling"),
> the problem still there. Then I revert to the previous revision, the
> problem goes away.
> So I think it's pretty much the side effect of MSI-X. However, as you
> mentioned that
> you didn't hit this problem, I'll ask the vendor to verify if this
> problem also happens on
> other machines with the same chip. Then we can determine to disable for specific
> mac version or just a certain subsystem id.
> 
Thanks a lot for testing. OK, I have one more idea.
AFAICS RTL8411 also has an integrated card reader controller which is driven
by module rtsx_pci. Maybe if both components (card reader controller + ethernet)
use different interrupt types, RTL8411 can't properly handle this.
In case module rtsx_pci is loaded on your system, can you check whether not
loading it (e.g. by blacklisting) or removing it makes a difference?

Can you provide the "lspci -v" output for the card reader part of RTL8411?

>>>>>>     I tried the latest 4.20 rc version but the problem still there. I
>>>>>> also tried some
>>>>>> hw_reset or init thing in the resume path but no effect. Any
>>>>>> suggestion for this?
>>>>>> Thanks
>>>>>>
>>>> Did previous kernel versions work? If it's a regression, a bisect would be
>>>> appreciated, because with the chip versions I've got I can't reproduce the issue.
>>>>
>>>>>> Chris
>>>>>
>>>>> Gentle ping. Any additional information required?
>>>>>
>>>>> Chris
>>>>>
>>>> Heiner
>>>
>>
> 

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