netdev - Re: [PATCH net-next v3 3/3] r8169: Enable ASPM for selected NICs

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Date:   Fri, 27 Aug 2021 14:23:07 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     nic_swsd <nic_swsd@...ltek.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Linux Netdev List <netdev@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v3 3/3] r8169: Enable ASPM for selected NICs

On Thu, Aug 19, 2021 at 5:56 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>
> On 19.08.2021 08:50, Kai-Heng Feng wrote:
> > On Thu, Aug 19, 2021 at 2:08 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
> >>
> >> On 19.08.2021 07:45, Kai-Heng Feng wrote:
> >>> The latest vendor driver enables ASPM for more recent r8168 NICs, so
> >>> disable ASPM on older chips and enable ASPM for the rest.
> >>>
> >>> Rename aspm_manageable to pcie_aspm_manageable to indicate it's ASPM
> >>> from PCIe, and use rtl_aspm_supported for Realtek NIC's internal ASPM
> >>> function.
> >>>
> >>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> >>> ---
> >>> v3:
> >>>  - Use pcie_aspm_supported() to retrieve ASPM support status
> >>>  - Use whitelist for r8169 internal ASPM status
> >>>
> >>> v2:
> >>>  - No change
> >>>
> >>>  drivers/net/ethernet/realtek/r8169_main.c | 27 ++++++++++++++++-------
> >>>  1 file changed, 19 insertions(+), 8 deletions(-)
> >>>
> >>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> >>> index 3359509c1c351..88e015d93e490 100644
> >>> --- a/drivers/net/ethernet/realtek/r8169_main.c
> >>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> >>> @@ -623,7 +623,8 @@ struct rtl8169_private {
> >>>       } wk;
> >>>
> >>>       unsigned supports_gmii:1;
> >>> -     unsigned aspm_manageable:1;
> >>> +     unsigned pcie_aspm_manageable:1;
> >>> +     unsigned rtl_aspm_supported:1;
> >>>       unsigned rtl_aspm_enabled:1;
> >>>       struct delayed_work aspm_toggle;
> >>>       atomic_t aspm_packet_count;
> >>> @@ -702,6 +703,20 @@ static bool rtl_is_8168evl_up(struct rtl8169_private *tp)
> >>>              tp->mac_version <= RTL_GIGA_MAC_VER_53;
> >>>  }
> >>>
> >>> +static int rtl_supports_aspm(struct rtl8169_private *tp)
> >>> +{
> >>> +     switch (tp->mac_version) {
> >>> +     case RTL_GIGA_MAC_VER_02 ... RTL_GIGA_MAC_VER_31:
> >>> +     case RTL_GIGA_MAC_VER_37:
> >>> +     case RTL_GIGA_MAC_VER_39:
> >>> +     case RTL_GIGA_MAC_VER_43:
> >>> +     case RTL_GIGA_MAC_VER_47:
> >>> +             return 0;
> >>> +     default:
> >>> +             return 1;
> >>> +     }
> >>> +}
> >>> +
> >>>  static bool rtl_supports_eee(struct rtl8169_private *tp)
> >>>  {
> >>>       return tp->mac_version >= RTL_GIGA_MAC_VER_34 &&
> >>> @@ -2669,7 +2684,7 @@ static void rtl_pcie_state_l2l3_disable(struct rtl8169_private *tp)
> >>>
> >>>  static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
> >>>  {
> >>> -     if (!tp->aspm_manageable && enable)
> >>> +     if (!(tp->pcie_aspm_manageable && tp->rtl_aspm_supported) && enable)
> >>>               return;
> >>>
> >>>       tp->rtl_aspm_enabled = enable;
> >>> @@ -5319,12 +5334,8 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >>>       if (rc)
> >>>               return rc;
> >>>
> >>> -     /* Disable ASPM completely as that cause random device stop working
> >>> -      * problems as well as full system hangs for some PCIe devices users.
> >>> -      */
> >>> -     rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S |
> >>> -                                       PCIE_LINK_STATE_L1);
> >>> -     tp->aspm_manageable = !rc;
> >>> +     tp->pcie_aspm_manageable = pcie_aspm_supported(pdev);
> >>
> >> That's not what I meant, and it's also not correct.
> >
> > In case I make another mistake in next series, let me ask it more clearly...
> > What you meant was to check both link->aspm_enabled and link->aspm_support?
> >
> aspm_enabled can be changed by the user at any time.

OK, will check that too.

> pci_disable_link_state() also considers whether BIOS forbids that OS
> mess with ASPM. See aspm_disabled.

I think aspm_disabled means leave BIOS ASPM setting intact?
So If PCIe ASPM is already enabled, we should also enable Realtek
specific bits to make ASPM really work.

>
> >>
> >>> +     tp->rtl_aspm_supported = rtl_supports_aspm(tp);
> >
> > Is rtl_supports_aspm() what you expect for the whitelist?
> > And what else am I missing?
> >
> I meant use rtl_supports_aspm() to check when ASPM is relevant at all,

I think that means the relevant bits are link->aspm_capable and
pcie_aspm_support_enabled().
ASPM can be already enabled by BIOS with aspm_disabled set.

Then check link->aspm_enabled in aspm_toggle() routine because it can
be enabled at runtime.

> and in addition use a blacklist for chip versions where ASPM is
> completely unusable.

Thanks for your suggestion and review.

Kai-Heng

>
> > Kai-Heng
> >
> >>>
> >>>       /* enable device (incl. PCI PM wakeup and hotplug setup) */
> >>>       rc = pcim_enable_device(pdev);
> >>>
> >>
>