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To:     Koba Ko <koba.ko@canonical.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
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From:   Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH] [v2] r8169: Use PHY_POLL when RTL8106E enable ASPM
Message-ID: <1b35b4ac-05a4-9a53-184b-33d2be20af58@gmail.com>
Date:   Thu, 10 Jun 2021 12:11:26 +0200
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On 10.06.2021 07:09, Koba Ko wrote:
> On Thu, Jun 10, 2021 at 12:12 AM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>
>> On 09.06.2021 17:23, Koba Ko wrote:
>>> On Wed, Jun 9, 2021 at 10:29 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>>>
>>>> On 09.06.2021 03:47, Koba Ko wrote:
>>>>> On Wed, Jun 9, 2021 at 4:58 AM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>>>>>
>>>>>> On 08.06.2021 16:17, Koba Ko wrote:
>>>>>>> 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;
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>>> 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.

You mean with the current rtl_hw_aspm_clkreq_enable(tp, true) you reach
only a lower pc state with RTL8168h?
Unfortunately Realtek doesn't release datasheets, therefore I don't
know the exact function of the affected registers/bits.


> 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
>>>>>>
>>>>>>
>>>>
>>