On 6/24/2019 10:03, Kai-Heng Feng wrote:
Hi Jeffrey,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.
at 19:08, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
Hi Jeffrey,Turns out the "extra sauceâ is not this part, itâs called âDynamic LTR supportâ.
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 18.104.22.168, but seems like 22.214.171.124 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.
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 */
/* 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.
Is there any plan to support this in the upstream kernel?Is there any plan to support Dynamic LTR in upstream e1000e?
S0ix support is under discussion with our architecture. We will try enable S0ix in our e1000e OOT driver as first step.
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