netdev - Re: RTL8402 stops working after hibernate/resume

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Date:   Thu, 24 Sep 2020 21:37:42 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Petr Tesarik <ptesarik@...e.cz>
Cc:     Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        netdev@...r.kernel.org
Subject: Re: RTL8402 stops working after hibernate/resume

On 24.09.2020 21:14, Petr Tesarik wrote:
> On Wed, 23 Sep 2020 11:57:41 +0200
> Heiner Kallweit <hkallweit1@...il.com> wrote:
> 
>> On 03.09.2020 10:41, Petr Tesarik wrote:
>>> Hi Heiner,
>>>
>>> this issue was on the back-burner for some time, but I've got some
>>> interesting news now.
>>>
>>> On Sat, 18 Jul 2020 14:07:50 +0200
>>> Heiner Kallweit <hkallweit1@...il.com> wrote:
>>>   
>>>> [...]
>>>> Maybe the following gives us an idea:
>>>> Please do "ethtool -d <if>" after boot and after resume from suspend,
>>>> and check for differences.  
>>>
>>> The register dump did not reveal anything of interest - the only
>>> differences were in the physical addresses after a device reopen.
>>>
>>> However, knowing that reloading the driver can fix the issue, I copied
>>> the initialization sequence from init_one() to rtl8169_resume() and
>>> gave it a try. That works!
>>>
>>> Then I started removing the initialization calls one by one. This
>>> exercise left me with a call to rtl_init_rxcfg(), which simply sets the
>>> RxConfig register. In other words, these is the difference between
>>> 5.8.4 and my working version:
>>>
>>> --- linux-orig/drivers/net/ethernet/realtek/r8169_main.c	2020-09-02 22:43:09.361951750 +0200
>>> +++ linux/drivers/net/ethernet/realtek/r8169_main.c	2020-09-03 10:36:23.915803703 +0200
>>> @@ -4925,6 +4925,9 @@
>>>  
>>>  	clk_prepare_enable(tp->clk);
>>>  
>>> +	if (tp->mac_version == RTL_GIGA_MAC_VER_37)
>>> +		RTL_W32(tp, RxConfig, RX128_INT_EN | RX_DMA_BURST);
>>> +
>>>  	if (netif_running(tp->dev))
>>>  		__rtl8169_resume(tp);
>>>  
>>> This is quite surprising, at least when the device is managed by
>>> NetworkManager, because then it is closed on wakeup, and the open
>>> method should call rtl_init_rxcfg() anyway. So, it might be a timing
>>> issue, or incorrect order of register writes.
>>>   
>> Thanks for the analysis. If you manually bring down and up the
>> interface, do you see the same issue?
> 
> I'm not quite sure what you mean, but if the interface is configured
> (and NetworkManager is stopped), I can do 'ip link set eth0 down' and
> then 'ip link set eth0 up', and the interface is fully functional.
> 
>> What is the value of RxConfig when entering the resume function?
> 
> I added a dev_info() to rtl8169_resume(). First with NetworkManager
> active (i.e. interface down on suspend):
> 
> [  525.956675] r8169 0000:03:00.2: RxConfig after resume: 0x0002400f
> 
> Then I re-tried with NetworkManager stopped (i.e. interface up on
> suspend). Same result:
> 
> [  785.413887] r8169 0000:03:00.2: RxConfig after resume: 0x0002400f
> 
Thanks for checking this. The value is not what I would have expected,
it may be a BIOS bug or HW issue with RTL8402. I'll slightly modify
your proposed patch and then let you re-test it.

> I hope that's what you were asking for...
> 
> Petr T
> 
Heiner