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

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Date:   Thu, 19 Aug 2021 11:56:11 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.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 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.
pci_disable_link_state() also considers whether BIOS forbids that OS
mess with ASPM. See aspm_disabled.

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

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