Re: [PATCH v2 1/2] r8169: Implement dynamic ASPM mechanism

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

On Fri, Aug 13, 2021 at 2:49 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> On 12.08.2021 17:53, Kai-Heng Feng wrote:
> > r8169 NICs on some platforms have abysmal speed when ASPM is enabled.
> > Same issue can be observed with older vendor drivers.
> >
> > The issue is however solved by the latest vendor driver. There's a new
> > mechanism, which disables r8169's internal ASPM when the NIC traffic has
> > more than 10 packets, and vice versa.
> >
> > Realtek confirmed that all their PCIe LAN NICs, r8106, r8168 and r8125
>
> As we have Realtek in this mail thread:

Is it still in active use? I always think it's just a dummy address...

> Typically hw issues affect 1-3 chip versions only. The ASPM problems seem
> to have been existing for at least 15 years now, in every chip version.
> It seems that even the new RTL8125 chip generation still has broken ASPM.

Is there a bug report for that?

> Why was this never fixed? ASPM not considered to be relevant? HW design
> too broken?

IIUC, ASPM is extremely relevant to pass EU/US power consumption
regulation. So I really don't know why the situation under Linux is so
dire.

Kai-Heng

>
> > use dynamic ASPM under Windows. So implement the same mechanism here to
> > resolve the issue.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> > ---
> > v2:
> >  - Use delayed_work instead of timer_list to avoid interrupt context
> >  - Use mutex to serialize packet counter read/write
> >  - Wording change
> >
> >  drivers/net/ethernet/realtek/r8169_main.c | 45 +++++++++++++++++++++++
> >  1 file changed, 45 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> > index c7af5bc3b8af..7ab2e841dc69 100644
> > --- a/drivers/net/ethernet/realtek/r8169_main.c
> > +++ b/drivers/net/ethernet/realtek/r8169_main.c
> > @@ -624,6 +624,11 @@ struct rtl8169_private {
> >
> >       unsigned supports_gmii:1;
> >       unsigned aspm_manageable:1;
> > +     unsigned aspm_enabled:1;
> > +     struct delayed_work aspm_toggle;
> > +     struct mutex aspm_mutex;
> > +     u32 aspm_packet_count;
> > +
> >       dma_addr_t counters_phys_addr;
> >       struct rtl8169_counters *counters;
> >       struct rtl8169_tc_offsets tc_offset;
> > @@ -2671,6 +2676,8 @@ static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
> >               RTL_W8(tp, Config5, RTL_R8(tp, Config5) & ~ASPM_en);
> >       }
> >
> > +     tp->aspm_enabled = enable;
> > +
> >       udelay(10);
> >  }
> >
> > @@ -4408,6 +4415,9 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp,
> >
> >       dirty_tx = tp->dirty_tx;
> >
> > +     mutex_lock(&tp->aspm_mutex);
> > +     tp->aspm_packet_count += tp->cur_tx - dirty_tx;
> > +     mutex_unlock(&tp->aspm_mutex);
> >       while (READ_ONCE(tp->cur_tx) != dirty_tx) {
> >               unsigned int entry = dirty_tx % NUM_TX_DESC;
> >               u32 status;
> > @@ -4552,6 +4562,10 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, int budget
> >               rtl8169_mark_to_asic(desc);
> >       }
> >
> > +     mutex_lock(&tp->aspm_mutex);
> > +     tp->aspm_packet_count += count;
> > +     mutex_unlock(&tp->aspm_mutex);
> > +
> >       return count;
> >  }
> >
> > @@ -4659,8 +4673,33 @@ static int r8169_phy_connect(struct rtl8169_private *tp)
> >       return 0;
> >  }
> >
> > +#define ASPM_PACKET_THRESHOLD 10
> > +#define ASPM_TOGGLE_INTERVAL 1000
> > +
> > +static void rtl8169_aspm_toggle(struct work_struct *work)
> > +{
> > +     struct rtl8169_private *tp = container_of(work, struct rtl8169_private,
> > +                                               aspm_toggle.work);
> > +     bool enable;
> > +
> > +     mutex_lock(&tp->aspm_mutex);
> > +     enable = tp->aspm_packet_count <= ASPM_PACKET_THRESHOLD;
> > +     tp->aspm_packet_count = 0;
> > +     mutex_unlock(&tp->aspm_mutex);
> > +
> > +     if (tp->aspm_enabled != enable) {
> > +             rtl_unlock_config_regs(tp);
> > +             rtl_hw_aspm_clkreq_enable(tp, enable);
> > +             rtl_lock_config_regs(tp);
> > +     }
> > +
> > +     schedule_delayed_work(&tp->aspm_toggle, ASPM_TOGGLE_INTERVAL);
> > +}
> > +
> >  static void rtl8169_down(struct rtl8169_private *tp)
> >  {
> > +     cancel_delayed_work_sync(&tp->aspm_toggle);
> > +
> >       /* Clear all task flags */
> >       bitmap_zero(tp->wk.flags, RTL_FLAG_MAX);
> >
> > @@ -4687,6 +4726,8 @@ static void rtl8169_up(struct rtl8169_private *tp)
> >       rtl_reset_work(tp);
> >
> >       phy_start(tp->phydev);
> > +
> > +     schedule_delayed_work(&tp->aspm_toggle, ASPM_TOGGLE_INTERVAL);
> >  }
> >
> >  static int rtl8169_close(struct net_device *dev)
> > @@ -5347,6 +5388,10 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >
> >       INIT_WORK(&tp->wk.work, rtl_task);
> >
> > +     INIT_DELAYED_WORK(&tp->aspm_toggle, rtl8169_aspm_toggle);
> > +
> > +     mutex_init(&tp->aspm_mutex);
> > +
> >       rtl_init_mac_address(tp);
> >
> >       dev->ethtool_ops = &rtl8169_ethtool_ops;
> >
>