Date:   Wed, 9 Jun 2021 16:29:21 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Koba Ko <koba.ko@...onical.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 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:
- 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.

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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