On Thu, 24 Sep 2020 22:12:24 +0200
Heiner Kallweit <hkallweit1@gmail.com> wrote:

> On 24.09.2020 21:14, Petr Tesarik wrote:
> > On Wed, 23 Sep 2020 11:57:41 +0200
> > Heiner Kallweit <hkallweit1@gmail.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@gmail.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
> > 
> > I hope that's what you were asking for...
> > 
> > Petr T
> > 
> 
> rtl8169_resume() has been changed in 5.9, therefore the patch doesn't
> apply cleanly on older kernel versions. Can you test the following
> on a 5.9-rc version or linux-next?

I tried installing 5.9-rc6, but it freezes hard at boot, last message is:

[   14.916259] libphy: r8169: probed

At this point, I suspect you're right that the BIOS is seriously buggy.
Let me check if ASUSTek has released any update for this model.

Thanks for your effort so far!

Petr T