Date:   Thu, 10 Jun 2021 13:09:57 +0800
From:   Koba Ko <koba.ko@...onical.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [v2] r8169: Use PHY_POLL when RTL8106E enable ASPM

On Thu, Jun 10, 2021 at 12:12 AM Heiner Kallweit <hkallweit1@...il.com> wrote:
>
> On 09.06.2021 17:23, Koba Ko wrote:
> > On Wed, Jun 9, 2021 at 10:29 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
> >>
> >> On 09.06.2021 03:47, Koba Ko wrote:
> >>> On Wed, Jun 9, 2021 at 4:58 AM Heiner Kallweit <hkallweit1@...il.com> wrote:
> >>>>
> >>>> On 08.06.2021 16:17, Koba Ko wrote:
> >>>>> On Tue, Jun 8, 2021 at 9:45 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
> >>>>>>
> >>>>>> On 08.06.2021 12:43, Koba Ko wrote:
> >>>>>>> On Tue, Jun 8, 2021 at 4:00 PM Heiner Kallweit <hkallweit1@...il.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@...onical.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;
> >>>>>>>>>
> >>>>>>>>
> >>>>>>
> >>>>
> >>>> The r8101 vendor driver applies a special setting for RTL8106e if ASPM is enabled.
> >>>> Not sure whether it's related but it's worth a try. Could you please check whether
> >>>> the following makes a difference?
> >>>
> >>> After applying this patch, it can't help relieve the issue.
> >>> The 8101 vendor driver also use polling method to watch the link change event.
> >>> Tried to disable polling method and enable LinkChg Irq, but it also
> >>> can't get LinkChg interrupt.
> >>>
> >> OK, thanks for testing.
> >> As it is now, rtl_phy_poll_quirk() would always return false because ASPM
> >> is disabled on driver load. Changing ASPM settings can be done later via sysfs
> >> if supported by device and upstream bridge. In addition:
> >
> > it seems a callback is needed to inform the driver when changing the
> > aspm policy,
> > is it correct?
> >
> It's not the policy that changes when writing to the link attributes.
> See aspm_attr_store_common(), it modifies link->aspm_disable and calls
> pcie_config_aspm_link(). Having said that there is no such callback.
> All that could be done is switching to polling for this chip version
> unconditionally.
>
> One more thing you could try is the following. The PCIe link will
> have L1 support enabled, but the NIC won't actively trigger it.
> This should be sufficient for the system to reach higher PC package
> power saving states.

After applying this patch, the issue can't be got.
I also tried to call rtl_hw_aspm_clkreq_enable(tp, false); on
rtl8169h/8111h on intel platform.
the machine could go deeper to pc10.
After tried this patch, I still think there's a hw issue on ASPM for rtl8106e.
How do you think which next step is better?

Im very appreciate your effort.
Thanks

>
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index b923958af..be162d2f5 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -3510,7 +3510,6 @@ static void rtl_hw_start_8106(struct rtl8169_private *tp)
>         rtl_eri_write(tp, 0x1b0, ERIAR_MASK_0011, 0x0000);
>
>         rtl_pcie_state_l2l3_disable(tp);
> -       rtl_hw_aspm_clkreq_enable(tp, true);
>  }
>
>  DECLARE_RTL_COND(rtl_mac_ocp_e00e_cond)
> --
> 2.32.0
>
>
>
>
> >> - If you want to return a bool, declare the return value as bool.
> >> - You shouldn't have to disable the LinkChg interrupt. The interrupt just triggers
> >>   a phylib state machine run what may result in a faster link-up signal even
> >>   when using polling.
> >
> > ok.
> >
> >>
> >> By the way: All Realtek vendor drivers (r8101, r8168, r8125) don't use the LinkChg
> >> interrupt. However I don't think this is because of known hw issues, more likely
> >> it's because they don't use phylib and thought polling is the easier approach.
> >> At least for r8169 I haven't heard yet of any complain regarding the LinkChg
> >> interrupt.
> >>
> >>>>
> >>>> diff --git a/drivers/net/ethernet/realtek/r8169_phy_config.c b/drivers/net/ethernet/realtek/r8169_phy_config.c
> >>>> index 50f0f621b..60014b9c4 100644
> >>>> --- a/drivers/net/ethernet/realtek/r8169_phy_config.c
> >>>> +++ b/drivers/net/ethernet/realtek/r8169_phy_config.c
> >>>> @@ -1153,6 +1153,7 @@ static void rtl8106e_hw_phy_config(struct rtl8169_private *tp,
> >>>>         r8169_apply_firmware(tp);
> >>>>
> >>>>         rtl_writephy_batch(phydev, phy_reg_init);
> >>>> +       phy_write(phydev, 0x18, 0x8310);
> >>>>  }
> >>>>
> >>>>  static void rtl8125_legacy_force_mode(struct phy_device *phydev)
> >>>> --
> >>>> 2.32.0
> >>>>
> >>>>
> >>
>

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