Re: R8169: Network lockups in 4.18.{8,9,10} (and 4.19 dev)

[Chris Clayton]

Too late at night to be doing this stuff. Clicked send instead of saving a draft. Sorry, please ignore.

On 10/10/2018 23:30, Chris Clayton wrote:
> OK, right kernel/module used this time. Please see findings below.
> 
> On 10/10/2018 01:24, Maciej S. Szmigiero wrote:
>> On 09.10.2018 22:36, Heiner Kallweit wrote:
>>> On 09.10.2018 16:40, Chris Clayton wrote:
>>>> Thanks to Maciej and Heiner for their replies.
>>>>
>>>> On 09/10/2018 13:32, Maciej S. Szmigiero wrote:
>>>>> On 07.10.2018 21:36, Chris Clayton wrote:
>>>>>> Hi again,
>>>>>>
>>>>>> I didn't think there was anything in 4.19-rc7 to fix this regression, but tried it anyway. I can confirm that the
>>>>>> regression is still present and my network still fails when, after a resume from suspend (to ram or disk), I open my
>>>>>> browser or my mail client. In both those cases the failure is almost immediate - e.g. my home page doesn't get displayed
>>>>>> in the browser. Pinging one of my ISPs name servers doesn't fail quite so quickly but the reported time increases from
>>>>>> 14-15ms to more than 1000ms.
>>>>>
>>>>> You can try comparing chip registers (ethtool -d eth0) in the working
>>>>> state (before a suspend) and in the broken state (after a resume).
>>>>> Maybe there will be some obvious in the difference.
>>>>>
>>>>> The same goes for the PCI configuration (lspci -d :8168 -vv).
>>>>>
>>>> Maciej suggested comparing the output from lspci -vv for the ethernet device. They are identical.
>>>>
>>>> Both Maciej and Heiner suggested comparing the output from "ethtool -d" pre and post suspend. Again, they are identical.
>>>> Heiner specifically suggested looking at the RxConfig. The value of that is 0x0002870e both pre and post suspend.
>>>>
>>> Hmm, this is very weird, especially taking into account that in your original
>>> report you state that removing the call to rtl_init_rxcfg() from rtl_hw_start()
>>> fixes the issue. rtl_init_rxcfg() deals with the RxConfig register only and
>>> register values seem to be the same before and after resume. So how can the
>>> chip behave differently?
>>> So far my best guess is that some chip quirk causes it to accept writes to
>>> register RxConfig, but to misinterpret or ignore the written value.
>>> So far your report is the only one (affecting RTL8411), but we don't know
>>> whether other chip versions are affected too.
>>
>> Also, it is interesting that even if one removes a call to
>> rtl_init_rxcfg() from rtl_hw_start() the RxConfig register will still get
>> written to moments later by rtl_set_rx_mode().
>>
>> The only chip accesses in the meantime seems to be a write to TxConfig by
>> rtl_set_tx_config_registers() and then a read of RxConfig plus two writes
>> to MAR0 earlier in rtl_set_rx_mode().
>>
>> My proposals are:
>> 1) Try swapping "rtl_init_rxcfg(tp);" and "rtl_set_tx_config_registers(tp);"
>> in rtl_hw_start().
>> Maybe the chip does not like sometimes that RxConfig is written before
>> TxConfig.
>>
> 
> This change made no difference. Networking still dies if I open a browser or leave ping running long enough.
> 
>> 2) Check the original value of RxConfig (after a resume) before
>> rtl_init_rxcfg() overwrites it (compile tested only):
>> --- r8169.c.ori
>> +++ r8169.c
>> @@ -5155,6 +5155,9 @@
>>  	/* Initially a 10 us delay. Turned it into a PCI commit. - FR */
>>  	RTL_R8(tp, IntrMask);
>>  	RTL_W8(tp, ChipCmd, CmdTxEnb | CmdRxEnb);
>> +
>> +	pr_notice("RxConfig before init was %.8x\n",
>> +		(unsigned int)RTL_R32(tp, RxConfig));
>>  	rtl_init_rxcfg(tp);
>>  	rtl_set_tx_config_registers(tp);
>>  
>>
>> This should be the value that you got when you removed the call to
>> rtl_init_rxcfg() for testing.
>> Now, knowing the "right" value you can experiment with what rtl_init_rxcfg()
>> writes (under the "default:" label for your NIC model).
> 
> This might be more interesting. Through combination of viewing the output from pr_notice() and the output from "ethtool
> -d", I can see RxConfig with the following values
> 
> 	During boot:	0x00028700
> 	Before suspend:	0x0002870e
> 	During resume:	0x00024000
> 	Post resume:	0x0002870e
> 
> I then removed the call to rtl_init_rxcfg() from rtl_hw_start() and rebuilt, installed and rebooted. Now I see the
> following values:
> 
> 	During boot:	0x00028700
> 	Before suspend:	0x0002870e
> 	During resume:	0x00024000
> 	Post resume:	0x0002870e
> 
>>
>> Hope this helps,
>> Maciej
>>