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From:   Koba Ko <koba.ko@canonical.com>
Date:   Tue, 8 Jun 2021 18:43:57 +0800
Message-ID: <CAJB-X+XFYa1cZgtJEL1KCNWviL3Y4X6EbN--rE8CD_9oD9EFyA@mail.gmail.com>
Subject: Re: [PATCH] [v2] r8169: Use PHY_POLL when RTL8106E enable ASPM
To:     Heiner Kallweit <hkallweit1@gmail.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tue, Jun 8, 2021 at 4:00 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> On 08.06.2021 05:22, Koba Ko wrote:
> > For RTL8106E, it's a Fast-ethernet chip.
> > If ASPM is enabled, the link chang interrupt wouldn't be triggered
> > immediately and must wait a very long time to get link change interrupt.
> > Even the link change interrupt isn't triggered, the phy link is already
> > established.
> >
> > Use PHY_POLL to watch the status of phy link and disable
> > the link change interrupt when ASPM is enabled on RTL8106E.
> >
> > v2: Instead use PHY_POLL and identify 8106E by RTL_GIGA_MAC_VER_39.
> >
>
> Still the issue description doesn't convince me that it's a hw bug
> with the respective chip version. What has been stated so far:
>
> 1. (and most important) Issue doesn't occur in mainline because ASPM
>    is disabled in mainline for r8169. Issue occurs only with a
>    downstream kernel with ASPM enabled for r8169.

mainline kernel and enable L1, the issue is also observed.

> 2. Issue occurs only with ASPM L1.1 not disabled, even though this chip
>    version doesn't support L1 sub-states. Just L0s/L1 don't trigger
>    the issue.
>    The NIC doesn't announce L1.1 support, therefore PCI core won't
>    enable L1 sub-states on the PCIe link between NIC and upstream
>    PCI bridge.

More precisely, when L1 is enabled, the issue would be triggered.
For RTL8106E,
1. Only disable L0s, pcie_aspm_enabled return 1, issue is triggered.
2. Only disable L1_1, pcie_aspm_enabled return 1, issue is triggered.

3. Only disable L1, pcie_aspm_enabled return 0, issue is not triggered.

>
> 3. Issue occurs only with a GBit-capable link partner. 100MBit link
>    partners are fine. Not clear whether issue occurs with a specific
>    Gbit link partner only or with GBit-capable link partners in general.
>
> 4. Only link-up interrupt is affected. Not link-down and not interrupts
>    triggered by other interrupt sources.
>
> 5. Realtek couldn't confirm that there's such a hw bug on RTL8106e.
>
> One thing that hasn't been asked yet:
> Does issue occur always if you re-plug the cable? Or only on boot?
> I'm asking because in the dmesg log you attached to the bugzilla issue
> the following looks totally ok.
>
> [   61.651643] r8169 0000:01:00.0 enp1s0: Link is Down
> [   63.720015] r8169 0000:01:00.0 enp1s0: Link is Up - 100Mbps/Full - flow control rx/tx
> [   66.685499] r8169 0000:01:00.0 enp1s0: Link is Down

Once the link is up,
1. If cable is unplug&plug immediately,  you wouldn't see the issue.
2. Unplug cable and wait a long time (~1Mins), then plug the cable,
the issue appears again.

>
> > Signed-off-by: Koba Ko <koba.ko@canonical.com>
> > ---
> >  drivers/net/ethernet/realtek/r8169_main.c | 21 +++++++++++++++++++--
> >  1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> > index 2c89cde7da1e..a59cbaef2839 100644
> > --- a/drivers/net/ethernet/realtek/r8169_main.c
> > +++ b/drivers/net/ethernet/realtek/r8169_main.c
> > @@ -4914,6 +4914,19 @@ static const struct dev_pm_ops rtl8169_pm_ops = {
> >
> >  #endif /* CONFIG_PM */
> >
> > +static int rtl_phy_poll_quirk(struct rtl8169_private *tp)
> > +{
> > +     struct pci_dev *pdev = tp->pci_dev;
> > +
> > +     if (!pcie_aspm_enabled(pdev))
>
> That's the wrong call. According to what you said earlier you want to
> check for L1 sub-states, not for ASPM in general.

As per described above, that's why use pcie_aspm_enabled here.

>
> > +             return 0;
> > +
> > +     if (tp->mac_version == RTL_GIGA_MAC_VER_39)
> > +             return 1;
> > +
> > +     return 0;
> > +}
> > +
> >  static void rtl_wol_shutdown_quirk(struct rtl8169_private *tp)
> >  {
> >       /* WoL fails with 8168b when the receiver is disabled. */
> > @@ -4991,7 +5004,10 @@ static const struct net_device_ops rtl_netdev_ops = {
> >
> >  static void rtl_set_irq_mask(struct rtl8169_private *tp)
> >  {
> > -     tp->irq_mask = RxOK | RxErr | TxOK | TxErr | LinkChg;
> > +     tp->irq_mask = RxOK | RxErr | TxOK | TxErr;
> > +
> > +     if (!rtl_phy_poll_quirk(tp))
> > +             tp->irq_mask |= LinkChg;
> >
> >       if (tp->mac_version <= RTL_GIGA_MAC_VER_06)
> >               tp->irq_mask |= SYSErr | RxOverflow | RxFIFOOver;
> > @@ -5085,7 +5101,8 @@ static int r8169_mdio_register(struct rtl8169_private *tp)
> >       new_bus->name = "r8169";
> >       new_bus->priv = tp;
> >       new_bus->parent = &pdev->dev;
> > -     new_bus->irq[0] = PHY_MAC_INTERRUPT;
> > +     new_bus->irq[0] =
> > +             (rtl_phy_poll_quirk(tp) ? PHY_POLL : PHY_MAC_INTERRUPT);
> >       snprintf(new_bus->id, MII_BUS_ID_SIZE, "r8169-%x", pci_dev_id(pdev));
> >
> >       new_bus->read = r8169_mdio_read_reg;
> >
>