Date:   Mon, 7 Jun 2021 12:43:04 +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] r8169: introduce polling method for link change

On 07.06.2021 06:34, Koba Ko wrote:
> On Fri, Jun 4, 2021 at 7:59 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>
>> On 04.06.2021 11:08, Koba Ko wrote:
>>> On Fri, Jun 4, 2021 at 4:23 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>>>
>>>> On 04.06.2021 09:22, Koba Ko wrote:
>>>>> On Thu, Jun 3, 2021 at 6:00 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>>>>>
>>>>>> On 03.06.2021 04:54, 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.
>>>>>>>
>>>>>> At first please provide a full dmesg log and output of lspci -vv.
>>>>>> Do you have the firmware for the NIC loaded? Please provide "ethtool -i <if>"
>>>>>> output.
>>>>>
>>>>> please get the logs from here,
>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=213165
>>>>>
>>>>>> Does the issue affect link-down and/or link-up detection?
>>>>>> Do you have runtime pm enabled? Then, after 10s of link-down NIC goes to
>>>>>> D3hot and link-up detection triggers a PME.
>>>>>
>>>>> Issue affect link-up.
>>>>> yes, pm runtime is enabled, but rtl8106e always stays D0 even if the
>>>>> cable isn't present.
>>>>>
>>>> Then runtime pm doesn't seem to be set to "auto". Else 10s after link loss
>>>> the chip runtime-suspends and is set to D3hot.
>>>
>>> I will check this.
>>>
>>>>
>>>>>>
>>>>>>> Introduce a polling method to watch the status of phy link and disable
>>>>>>> the link change interrupt.
>>>>>>> Also add a quirk for those realtek devices have the same issue.
>>>>>>>
>>>>>> Which are the affected chip versions? Did you check with Realtek?
>>>>>> Your patch switches to polling for all Fast Ethernet versions,
>>>>>> and that's not what we want.
>>>>>
>>>>> I don't know the exact version, only the chip name 806e(pci device id 0x8165).
>>>>> ok, Im asking Realtek to help how to identify the chip issue is observed.
>>>>>
>>>> At least your Bugzilla report refers to VER_39. PCI device id 0x8136 is shared
>>>> by all fast ethernet chip versions.
>>>> Do you know other affected chip versions apart from VER_39 ?
>>>>
>>>> In the Bugzilla report you also write the issue occurs with GBit-capable
>>>> link partners. This sounds more like an aneg problem.
>>>> The issue doesn't occur with fast ethernet link partners?
>>>
>>> Issue wouldn't be observed when the link-partner has only FE capability.
>>>
>> Weird. I still have no clue how FE vs. GE support at link partner and
>> ASPM could be related. I could understand that the PHY might have a
>> problem with a GE link partner and aneg takes more time than usual.
>> But this would be completely unrelated to a potential issue with
>> ASPM on the PCIe link.
>>
>> And it's also not clear how L1_1 can cause an issue if the NIC doesn't
>> support L1 sub-states. Maybe the root cause isn't with the NIC but
>> with some other component in the PCIe path (e.g. bridge).
>>
> 
> I prefer that there's a interrupt issue when aspm is enabled on RTL8106e,
> 
>>>>
>>>> Your bug report also includes a patch that disables L1_1 only.
>>>> Not sure how this is related because the chip version we speak about
>>>> here doesn't support L1 sub-states.
>>>
>>> I have tried to enable L0s, L1 and don't disable L1 substate,
>>> but still get the issue that interrupt can't be fired immediately but
>>> the Link status is up.
>>>
>>>>
>>>>>>
>>>>>> My suspicion would be that something is system-dependent. Else I think
>>>>>> we would have seen such a report before.
>>>>> On the mainline, the aspm is disable, so you may not observe this.
>>>>> If you enable ASPM and must wait CHIP go to power-saving mode, then
>>>>> you can observe the issue.
>>>>>>
>>>>
>>>> So what you're saying is that mainline is fine and your problem is with
>>>> a downstream kernel with re-enabled ASPM? So there's nothing broken in
>>>> mainline? In mainline you have the option to re-enable ASPM states
>>>> individually via sysfs (link subdir at pci device).
>>>
>>> If enable L1_1 on the mainline, the issue could be observed too.
>>>
>> It has a reason that ASPM is disabled per default in mainline. Different
>> chip versions have different types of issues with ASPM enabled.
>> However several chip versions work fine with ASPM (also LI sub-states),
>> therefore users can re-enable ASPM states at own risk.
> 
> After consulting with REALTEK, I can identify RTL8106e by PCI_VENDOR
> REALTEK, DEVICE 0x8136, Revision 0x7.

This wasn't the question. The identification is available already.
This chip version is RTL_GIGA_MAC_VER_39.

> I would like to make PHY_POLL as default for RTL8106E on V2.
> because there's no side effects besides the cpu usage rate would be a
> little higher,
> How do you think?
> 
Did you check the actual question with Realtek? Did they confirm a hw
issue with this chip version? If yes, some more details would be helpful.

The dmesg log attached to your linked bugzilla issue lists a number of
ACPI errors. Overall I'm still not convinced that root cause of your
issue is a NIC hw bug.

>>> Thanks
>>>>
>>>>>>> Signed-off-by: Koba Ko <koba.ko@...onical.com>
>>>>>>> ---
>>>>>>>  drivers/net/ethernet/realtek/r8169.h      |   2 +
>>>>>>>  drivers/net/ethernet/realtek/r8169_main.c | 112 ++++++++++++++++++----
>>>>>>>  2 files changed, 98 insertions(+), 16 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/net/ethernet/realtek/r8169.h b/drivers/net/ethernet/realtek/r8169.h
>>>>>>> index 2728df46ec41..a8c71adb1b57 100644
>>>>>>> --- a/drivers/net/ethernet/realtek/r8169.h
>>>>>>> +++ b/drivers/net/ethernet/realtek/r8169.h
>>>>>>> @@ -11,6 +11,8 @@
>>>>>>>  #include <linux/types.h>
>>>>>>>  #include <linux/phy.h>
>>>>>>>
>>>>>>> +#define RTL8169_LINK_TIMEOUT (1 * HZ)
>>>>>>> +
>>>>>>>  enum mac_version {
>>>>>>>       /* support for ancient RTL_GIGA_MAC_VER_01 has been removed */
>>>>>>>       RTL_GIGA_MAC_VER_02,
>>>>>>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
>>>>>>> index 2c89cde7da1e..70aacc83d641 100644
>>>>>>> --- a/drivers/net/ethernet/realtek/r8169_main.c
>>>>>>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
>>>>>>> @@ -178,6 +178,11 @@ static const struct pci_device_id rtl8169_pci_tbl[] = {
>>>>>>>
>>>>>>>  MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
>>>>>>>
>>>>>>> +static const struct pci_device_id rtl8169_linkChg_polling_enabled[] = {
>>>>>>> +     { PCI_VDEVICE(REALTEK, 0x8136), RTL_CFG_NO_GBIT },
>>>>>>> +     { 0 }
>>>>>>> +};
>>>>>>> +
>>>>>>
>>>>>> This doesn't seem to be used.
>>>>>>
>>>>>>>  enum rtl_registers {
>>>>>>>       MAC0            = 0,    /* Ethernet hardware address. */
>>>>>>>       MAC4            = 4,
>>>>>>> @@ -618,6 +623,7 @@ struct rtl8169_private {
>>>>>>>       u16 cp_cmd;
>>>>>>>       u32 irq_mask;
>>>>>>>       struct clk *clk;
>>>>>>> +     struct timer_list link_timer;
>>>>>>>
>>>>>>>       struct {
>>>>>>>               DECLARE_BITMAP(flags, RTL_FLAG_MAX);
>>>>>>> @@ -1179,6 +1185,16 @@ static void rtl8168ep_stop_cmac(struct rtl8169_private *tp)
>>>>>>>       RTL_W8(tp, IBCR0, RTL_R8(tp, IBCR0) & ~0x01);
>>>>>>>  }
>>>>>>>
>>>>>>> +static int rtl_link_chng_polling_quirk(struct rtl8169_private *tp)
>>>>>>> +{
>>>>>>> +     struct pci_dev *pdev = tp->pci_dev;
>>>>>>> +
>>>>>>> +     if (pdev->vendor == 0x10ec && pdev->device == 0x8136 && !tp->supports_gmii)
>>>>>>> +             return 1;
>>>>>>> +
>>>>>>> +     return 0;
>>>>>>> +}
>>>>>>> +
>>>>>>>  static void rtl8168dp_driver_start(struct rtl8169_private *tp)
>>>>>>>  {
>>>>>>>       r8168dp_oob_notify(tp, OOB_CMD_DRIVER_START);
>>>>>>> @@ -4608,6 +4624,75 @@ static void rtl_task(struct work_struct *work)
>>>>>>>       rtnl_unlock();
>>>>>>>  }
>>>>>>>
>>>>>>> +static void r8169_phylink_handler(struct net_device *ndev)
>>>>>>> +{
>>>>>>> +     struct rtl8169_private *tp = netdev_priv(ndev);
>>>>>>> +
>>>>>>> +     if (netif_carrier_ok(ndev)) {
>>>>>>> +             rtl_link_chg_patch(tp);
>>>>>>> +             pm_request_resume(&tp->pci_dev->dev);
>>>>>>> +     } else {
>>>>>>> +             pm_runtime_idle(&tp->pci_dev->dev);
>>>>>>> +     }
>>>>>>> +
>>>>>>> +     if (net_ratelimit())
>>>>>>> +             phy_print_status(tp->phydev);
>>>>>>> +}
>>>>>>> +
>>>>>>> +static unsigned int
>>>>>>> +rtl8169_xmii_link_ok(struct net_device *dev)
>>>>>>> +{
>>>>>>> +     struct rtl8169_private *tp = netdev_priv(dev);
>>>>>>> +     unsigned int retval;
>>>>>>> +
>>>>>>> +     retval = (RTL_R8(tp, PHYstatus) & LinkStatus) ? 1 : 0;
>>>>>>> +
>>>>>>> +     return retval;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static void
>>>>>>> +rtl8169_check_link_status(struct net_device *dev)
>>>>>>> +{
>>>>>>> +     struct rtl8169_private *tp = netdev_priv(dev);
>>>>>>> +     int link_status_on;
>>>>>>> +
>>>>>>> +     link_status_on = rtl8169_xmii_link_ok(dev);
>>>>>>> +
>>>>>>> +     if (netif_carrier_ok(dev) == link_status_on)
>>>>>>> +             return;
>>>>>>> +
>>>>>>> +     phy_mac_interrupt(tp->phydev);
>>>>>>> +
>>>>>>> +     r8169_phylink_handler (dev);
>>>>>>> +}
>>>>>>> +
>>>>>>> +static void rtl8169_link_timer(struct timer_list *t)
>>>>>>> +{
>>>>>>> +     struct rtl8169_private *tp = from_timer(tp, t, link_timer);
>>>>>>> +     struct net_device *dev = tp->dev;
>>>>>>> +     struct timer_list *timer = t;
>>>>>>> +     unsigned long flags;
>>>>>>
>>>>>> flags isn't used and triggers a compiler warning. Did you even
>>>>>> compile-test your patch?
>>>>>>
>>>>>>> +
>>>>>>> +     rtl8169_check_link_status(dev);
>>>>>>> +
>>>>>>> +     if (timer_pending(&tp->link_timer))
>>>>>>> +             return;
>>>>>>> +
>>>>>>> +     mod_timer(timer, jiffies + RTL8169_LINK_TIMEOUT);
>>>>>>> +}
>>>>>>> +
>>>>>>> +static inline void rtl8169_delete_link_timer(struct net_device *dev, struct timer_list *timer)
>>>>>>> +{
>>>>>>> +     del_timer_sync(timer);
>>>>>>> +}
>>>>>>> +
>>>>>>> +static inline void rtl8169_request_link_timer(struct net_device *dev)
>>>>>>> +{
>>>>>>> +     struct rtl8169_private *tp = netdev_priv(dev);
>>>>>>> +
>>>>>>> +     timer_setup(&tp->link_timer, rtl8169_link_timer, TIMER_INIT_FLAGS);
>>>>>>> +}
>>>>>>> +
>>>>>>>  static int rtl8169_poll(struct napi_struct *napi, int budget)
>>>>>>>  {
>>>>>>>       struct rtl8169_private *tp = container_of(napi, struct rtl8169_private, napi);
>>>>>>> @@ -4624,21 +4709,6 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
>>>>>>>       return work_done;
>>>>>>>  }
>>>>>>>
>>>>>>> -static void r8169_phylink_handler(struct net_device *ndev)
>>>>>>> -{
>>>>>>> -     struct rtl8169_private *tp = netdev_priv(ndev);
>>>>>>> -
>>>>>>> -     if (netif_carrier_ok(ndev)) {
>>>>>>> -             rtl_link_chg_patch(tp);
>>>>>>> -             pm_request_resume(&tp->pci_dev->dev);
>>>>>>> -     } else {
>>>>>>> -             pm_runtime_idle(&tp->pci_dev->dev);
>>>>>>> -     }
>>>>>>> -
>>>>>>> -     if (net_ratelimit())
>>>>>>> -             phy_print_status(tp->phydev);
>>>>>>> -}
>>>>>>> -
>>>>>>>  static int r8169_phy_connect(struct rtl8169_private *tp)
>>>>>>>  {
>>>>>>>       struct phy_device *phydev = tp->phydev;
>>>>>>> @@ -4769,6 +4839,10 @@ static int rtl_open(struct net_device *dev)
>>>>>>>               goto err_free_irq;
>>>>>>>
>>>>>>>       rtl8169_up(tp);
>>>>>>> +
>>>>>>> +     if (rtl_link_chng_polling_quirk(tp))
>>>>>>> +             mod_timer(&tp->link_timer, jiffies + RTL8169_LINK_TIMEOUT);
>>>>>>> +
>>>>>>>       rtl8169_init_counter_offsets(tp);
>>>>>>>       netif_start_queue(dev);
>>>>>>>  out:
>>>>>>> @@ -4991,7 +5065,10 @@ 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_link_chng_polling_quirk(tp))
>>>>>>> +             tp->irq_mask |= LinkChg;
>>>>>>>
>>>>>>>       if (tp->mac_version <= RTL_GIGA_MAC_VER_06)
>>>>>>>               tp->irq_mask |= SYSErr | RxOverflow | RxFIFOOver;
>>>>>>> @@ -5436,6 +5513,9 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>>>>>>>       if (pci_dev_run_wake(pdev))
>>>>>>>               pm_runtime_put_sync(&pdev->dev);
>>>>>>>
>>>>>>> +     if (rtl_link_chng_polling_quirk(tp))
>>>>>>> +             rtl8169_request_link_timer(dev);
>>>>>>> +
>>>>>>>       return 0;
>>>>>>>  }
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> All this isn't needed. If you want to switch to link status polling,
>>>>>> why don't you simply let phylib do it? PHY_MAC_INTERRUPT -> PHY_POLL
>>>>>
>>>>> Thanks for suggestions, I tried to use PHY_POLL, it could do the same
>>>>> thing that I did.
>>>>>
>>>>>> Your timer-based code most likely would have problems if runtime pm
>>>>>> is enabled. Then you try to read the link status whilst NIC is in
>>>>>> D3hot.
>>>>
>>

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