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Date:   Thu, 24 Sep 2020 21:14:44 +0200
From:   Petr Tesarik <ptesarik@...e.cz>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        netdev@...r.kernel.org
Subject: Re: RTL8402 stops working after hibernate/resume

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

I hope that's what you were asking for...

Petr T

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