Re: [Intel-wired-lan] Opportunistic S0ix blocked by e1000e when ethernet is in use

[Neftin, Sasha]

On 6/24/2019 10:03, Kai-Heng Feng wrote:
> Hi Jeffrey,
>
> at 19:08, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
>
> > Hi Jeffrey,
> >
> > There are several platforms that uses e1000e canât enter Opportunistic 
> > S0ix (PC10) when the ethernet has a link partner.
> >
> > This behavior also exits in out-of-tree e1000e driver 3.4.2.1, but 
> > seems like 3.4.2.3 fixes the issue.
> >
> > A quick diff between the two versions shows that this code section may 
> > be our solution:
> >
> > ÂÂÂÂÂÂÂ /* Read from EXTCNF_CTRL in e1000_acquire_swflag_ich8lan function
> > ÂÂÂÂÂÂÂÂ * may occur during global reset and cause system hang.
> > ÂÂÂÂÂÂÂÂ * Configuration space access creates the needed delay.
> > ÂÂÂÂÂÂÂÂ * Write to E1000_STRAP RO register 
> > E1000_PCI_VENDOR_ID_REGISTER value
> > ÂÂÂÂÂÂÂÂ * insures configuration space read is done before global reset.
> > ÂÂÂÂÂÂÂÂ */
> > ÂÂÂÂÂÂÂ pci_read_config_word(hw->adapter->pdev, 
> > E1000_PCI_VENDOR_ID_REGISTER,
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &pci_cfg);
> > ÂÂÂÂÂÂÂ ew32(STRAP, pci_cfg);
> > ÂÂÂÂÂÂÂ e_dbg("Issuing a global reset to ich8lan\n");
> > ÂÂÂÂÂÂÂ ew32(CTRL, (ctrl | E1000_CTRL_RST));
> > ÂÂÂÂÂÂÂ /* cannot issue a flush here because it hangs the hardware */
> > ÂÂÂÂÂÂÂ msleep(20);
> >
> > ÂÂÂÂÂÂÂ /* Configuration space access improve HW level time sync 
> > mechanism.
> > ÂÂÂÂÂÂÂÂ * Write to E1000_STRAP RO register E1000_PCI_VENDOR_ID_REGISTER
> > ÂÂÂÂÂÂÂÂ * value to insure configuration space read is done
> > ÂÂÂÂÂÂÂÂ * before any access to mac register.
> > ÂÂÂÂÂÂÂÂ */
> > ÂÂÂÂÂÂÂ pci_read_config_word(hw->adapter->pdev, 
> > E1000_PCI_VENDOR_ID_REGISTER,
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &pci_cfg);
> > ÂÂÂÂÂÂÂ ew32(STRAP, pci_cfg);
>
> Turns out the "extra sauceâ is not this part, itâs called âDynamic LTR 
> supportâ.
> >>
> > Is there any plan to support this in the upstream kernel?
>
> Is there any plan to support Dynamic LTR in upstream e1000e?
Dynamic LTR is not stable solution. So, we can not put this solution to 
upstream. I hope we will be able to fix this in HW for a future projects.
S0ix support is under discussion with our architecture. We will try 
enable S0ix in our e1000e OOT driver as first step.
> Kai-Heng
>
> > Kai-Heng
>
>
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Thanks
Sasha