netdev - Re: [Intel-wired-lan] [PATCH 2/2] igc: wait for the MAC copy when enabled MAC passthrough

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Date:   Thu, 8 Jul 2021 07:24:35 +0300
From:   "Neftin, Sasha" <sasha.neftin@...el.com>
To:     Aaron Ma <aaron.ma@...onical.com>, jesse.brandeburg@...el.com,
        anthony.l.nguyen@...el.com, davem@...emloft.net, kuba@...nel.org,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Edri, Michael" <michael.edri@...el.com>,
        "Ruinskiy, Dima" <dima.ruinskiy@...el.com>,
        "Shalev, Avi" <avi.shalev@...el.com>
Subject: Re: [Intel-wired-lan] [PATCH 2/2] igc: wait for the MAC copy when
 enabled MAC passthrough

On 7/6/2021 09:46, Aaron Ma wrote:
> 
> On 7/5/21 7:54 PM, Neftin, Sasha wrote:
>> Hello Aaron, Thanks to point me on this document. I see... This is 
>> recommendation for Windows driver. Anyway, "delay" approach is 
>> error-prone. We need rather ask for MNG FW confirmation (message) that 
>> MAC address is copied.
>> Can we call (in case we know that MNG FW copied MAC address):
>> igc_rar_set (method from igc_mac.c), update the mac.addr and then 
>> perform": memcpy(netdev->dev_addr, hw->mac.addr, netdev->addr_len);?
> 
> Without delay, after igc_rar_set, the MAC address is all 0.
> The MAC addr is the from dock instead of MAC passthrough with the 
> original driver.
I would to like suggest checking the following direction:
1. principal question: can we update the netdev device address after it 
is already set during probe? I meant perform another:
memcpy(netdev->dev_addr, hw->mac.addr, netdev->addr_len) up to demand
2. We need to work with Intel's firmware engineer/group and define the 
message/event: MAC addressis changed and should be updated.
As I know MNG FW updates shadow registers. Since shadow registers are 
different from RAL/RAH registers - it could be a notification that the 
MAC address changed. Let's check it.
> 
> Thanks,
> Aaron