Opportunistic S0ix blocked by e1000e when ethernet is in use

[Kai-Heng Feng]

Hi Jeffrey,

There are several platforms that uses e1000e can’t 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:

        /* Read from EXTCNF_CTRL in e1000_acquire_swflag_ich8lan function
         * may occur during global reset and cause system hang.
         * Configuration space access creates the needed delay.
         * Write to E1000_STRAP RO register E1000_PCI_VENDOR_ID_REGISTER value
         * insures configuration space read is done before global reset.
         */
        pci_read_config_word(hw->adapter->pdev, E1000_PCI_VENDOR_ID_REGISTER,
                             &pci_cfg);
        ew32(STRAP, pci_cfg);
        e_dbg("Issuing a global reset to ich8lan\n");
        ew32(CTRL, (ctrl | E1000_CTRL_RST));
        /* cannot issue a flush here because it hangs the hardware */
        msleep(20);

        /* Configuration space access improve HW level time sync mechanism.
         * Write to E1000_STRAP RO register E1000_PCI_VENDOR_ID_REGISTER
         * value to insure configuration space read is done
         * before any access to mac register.
         */
        pci_read_config_word(hw->adapter->pdev, E1000_PCI_VENDOR_ID_REGISTER,
                             &pci_cfg);
        ew32(STRAP, pci_cfg);

Is there any plan to support this in the upstream kernel?

Kai-Heng