Re: [Intel-wired-lan] [PATCH 2/3] e1000e: Make mei_me active when e1000e is in use

[Kai-Heng Feng]

Hi Sasha,

On Wed, Jul 14, 2021 at 1:39 PM Sasha Neftin <sasha.neftin@xxxxxxxxx> wrote:
>
> On 7/12/2021 16:34, Kai-Heng Feng wrote:
> > Many users report rather sluggish RX speed on TGP I219. Since
> > "intel_idle.max_cstate=1" doesn't help, so it's not caused by deeper
> > package C-state.
> >
> > A workaround that always works is to make sure mei_me is runtime active
> > when e1000e is in use.
> >
> > The root cause is still unknown, but since many users are affected by
> > the issue, implment the quirk in the driver as a temporary workaround.
> Hello Kai-Heng,
> First - thanks for the investigation of this problem. As I know CSME/AMT
> not POR on Linux and not supported. Recently we started add support for
> CSME/AMT none provisioned version (handshake with CSME in s0ix flow -
> only CSME with s0ix will support). It is not related to rx bandwidth
> problem.

I am aware that ME is not POR under Linux, so the commit message
states clearly that the patch is just a "temporary workaround".
Not every laptop can disable ME/AMT, and I don't think asking user to
fiddle with BIOS is a good thing, hence the patch.

> I do not know how MEI driver affect 1Gbe driver - so, I would suggest to
> involve our CSME engineer (alexander.usyskin@xxxxxxxxx) and try to
> investigate this problem.
> Does this problem observed on Dell systems? As I heard no reproduction
> on Intel's RVP platform.
> Another question: does disable mei_me runpm solve your problem?

Yes, disabling runpm on mei_me can workaround the issue, and that's
essentially what this patch does by adding DL_FLAG_PM_RUNTIME |
DL_FLAG_RPM_ACTIVE flag.

Kai-Heng

> >
> > Also adds mei_me as soft dependency to ensure the device link can be
> > created if e1000e is in initramfs.
> >
> > BugLink: https://bugs.launchpad.net/bugs/1927925
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213377
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213651
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/intel/e1000e/netdev.c | 26 ++++++++++++++++++++++
> >   1 file changed, 26 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
> > index 5835d6cf2f51..e63445a8ce12 100644
> > --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> > +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> > @@ -7317,6 +7317,27 @@ static const struct net_device_ops e1000e_netdev_ops = {
> >       .ndo_features_check     = passthru_features_check,
> >   };
> >
> > +static void e1000e_create_device_links(struct pci_dev *pdev)
> > +{
> > +     struct pci_dev *tgp_mei_me;
> > +
> > +     /* Find TGP mei_me devices and make e1000e power depend on mei_me */
> > +     tgp_mei_me = pci_get_device(PCI_VENDOR_ID_INTEL, 0xa0e0, NULL);
> > +     if (!tgp_mei_me) {
> > +             tgp_mei_me = pci_get_device(PCI_VENDOR_ID_INTEL, 0x43e0, NULL);
> > +             if (!tgp_mei_me)
> > +                     return;
> > +     }
> > +
> > +     if (device_link_add(&pdev->dev, &tgp_mei_me->dev,
> > +                         DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE |
> > +                         DL_FLAG_AUTOREMOVE_CONSUMER))
> > +             pci_info(pdev, "System and runtime PM depends on %s\n",
> > +                      pci_name(tgp_mei_me));
> > +
> > +     pci_dev_put(tgp_mei_me);
> > +}
> > +
> >   /**
> >    * e1000_probe - Device Initialization Routine
> >    * @pdev: PCI device information struct
> > @@ -7645,6 +7666,9 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >       if (pci_dev_run_wake(pdev) && hw->mac.type != e1000_pch_cnp)
> >               pm_runtime_put_noidle(&pdev->dev);
> >
> > +     if (hw->mac.type == e1000_pch_tgp)
> > +             e1000e_create_device_links(pdev);
> > +
> >       return 0;
> >
> >   err_register:
> > @@ -7917,6 +7941,8 @@ static void __exit e1000_exit_module(void)
> >   }
> >   module_exit(e1000_exit_module);
> >
> > +/* Ensure device link can be created if e1000e is in the initramfs. */
> > +MODULE_SOFTDEP("pre: mei_me");
> >   MODULE_AUTHOR("Intel Corporation, <linux.nics@xxxxxxxxx>");
> >   MODULE_DESCRIPTION("Intel(R) PRO/1000 Network Driver");
> >   MODULE_LICENSE("GPL v2");
> >
> Thanks,Sasha