linux-kernel - Re: [Intel-wired-lan] [PATCH v4] e1000e: Increase polling timeout on MDIC ready bit

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Date:   Tue, 29 Sep 2020 21:31:27 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     "Neftin, Sasha" <sasha.neftin@...el.com>
Cc:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Andrew Lunn <andrew@...n.ch>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:INTEL ETHERNET DRIVERS" 
        <intel-wired-lan@...ts.osuosl.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Lifshits, Vitaly" <vitaly.lifshits@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>
Subject: Re: [Intel-wired-lan] [PATCH v4] e1000e: Increase polling timeout on
 MDIC ready bit

Hi Sasha,

> On Sep 29, 2020, at 21:08, Neftin, Sasha <sasha.neftin@...el.com> wrote:
> 
> On 9/28/2020 11:36, Kai-Heng Feng wrote:
>> We are seeing the following error after S3 resume:
>> [  704.746874] e1000e 0000:00:1f.6 eno1: Setting page 0x6020
>> [  704.844232] e1000e 0000:00:1f.6 eno1: MDI Write did not complete
>> [  704.902817] e1000e 0000:00:1f.6 eno1: Setting page 0x6020
>> [  704.903075] e1000e 0000:00:1f.6 eno1: reading PHY page 769 (or 0x6020 shifted) reg 0x17
>> [  704.903281] e1000e 0000:00:1f.6 eno1: Setting page 0x6020
>> [  704.903486] e1000e 0000:00:1f.6 eno1: writing PHY page 769 (or 0x6020 shifted) reg 0x17
>> [  704.943155] e1000e 0000:00:1f.6 eno1: MDI Error
>> ...
>> [  705.108161] e1000e 0000:00:1f.6 eno1: Hardware Error
>> As Andrew Lunn pointed out, MDIO has nothing to do with phy, and indeed
>> increase polling iteration can resolve the issue.
>> This patch only papers over the symptom, as we don't really know the
>> root cause of the issue. The most possible culprit is Intel ME, which
>> may do its own things that conflict with software.
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> v4:
>>  - States that this patch just papers over the symptom.
>> v3:
>>  - Moving delay to end of loop doesn't save anytime, move it back.
>>  - Point out this is quitely likely caused by Intel ME.
>> v2:
>>  - Increase polling iteration instead of powering down the phy.
>>  drivers/net/ethernet/intel/e1000e/phy.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/drivers/net/ethernet/intel/e1000e/phy.c b/drivers/net/ethernet/intel/e1000e/phy.c
>> index e11c877595fb..e6d4acd90937 100644
>> --- a/drivers/net/ethernet/intel/e1000e/phy.c
>> +++ b/drivers/net/ethernet/intel/e1000e/phy.c
>> @@ -203,7 +203,7 @@ s32 e1000e_write_phy_reg_mdic(struct e1000_hw *hw, u32 offset, u16 data)
>>  	 * Increasing the time out as testing showed failures with
>>  	 * the lower time out
>>  	 */
>> -	for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 3); i++) {
>> +	for (i = 0; i < (E1000_GEN_POLL_TIMEOUT * 10); i++) {
> As we discussed (many threads) - AMT/ME systems not supported on Linux as properly. I do not think increasing polling iteration will solve the problem. Rather mask it.

I am aware of the status quo of no proper support on Intel ME. 

> I prefer you check option to disable ME vi BIOS on your system.

We can't ask user to change the BIOS to accommodate Linux. So before a proper solution comes out, masking the problem is good enough for me.
Until then, I'll carry it as a downstream distro patch.

Kai-Heng

>>  		udelay(50);
>>  		mdic = er32(MDIC);
>>  		if (mdic & E1000_MDIC_READY)
> Thanks,
> Sasha