Date:   Mon, 7 Jun 2021 12:34:32 +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] r8169: introduce polling method for link change

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.
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?

> > 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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