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From:   Koba Ko <koba.ko@canonical.com>
Date:   Tue, 8 Jun 2021 22:17:45 +0800
Message-ID: <CAJB-X+V78kUM97AZQp9ZQbp=tzWwD9FQWEcFS6VnVRZnSHkb7g@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 9:45 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> On 08.06.2021 12:43, Koba Ko wrote:
> > 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.
> >
> Yes, but enabling L1 via sysfs is at own risk.

but we could have a workaround if hw have an aspm issue.

>
> >> 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.
> >
> This sounds runtime-pm-related. After 10s the NIC runtime-suspends,
> and once the cable is re-plugged a PME is triggered that lets the
> PCI core return the PCIe link from D3hot to D0.
> If you re-plug the cable after such a longer time, do you see the
> PCIe PME immediately in /proc/interrupts?

I don't know which irq number is for RTL8106e PME, but check all PME
in /proc/interrupt,

There's no interrupt increase on all PME entries and rtl8106e irq entry(irq 32).

>
> And if you set /sys/class/net/<if>/power/control to "on", does the
> issue still occur?

Yes, after echo "on" to /sys/class/net/<if>/power/control and
replugging the cable, the issue is still caught.
>
> >>
> >>> 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;
> >>>
> >>
>