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

On 7/5/2021 10:38, Aaron Ma wrote:

On 7/4/21 1:36 PM, Neftin, Sasha wrote:

quoted

On 7/2/2021 07:51, Aaron Ma wrote:

quoted

Such as dock hot plug event when runtime, for hardware implementation,
the MAC copy takes less than one second when BIOS enabled MAC 
passthrough.
After test on Lenovo TBT4 dock, 600ms is enough to update the
MAC address.
Otherwise ethernet fails to work.

Signed-off-by: Aaron Ma <redacted>
---
  drivers/net/ethernet/intel/igc/igc_main.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c 

b/drivers/net/ethernet/intel/igc/igc_main.c
index 606b72cb6193..c8bc5f089255 100644

--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c

@@ -5468,6 +5468,9 @@ static int igc_probe(struct pci_dev *pdev,

      memcpy(&hw->mac.ops, ei->mac_ops, sizeof(hw->mac.ops));
      memcpy(&hw->phy.ops, ei->phy_ops, sizeof(hw->phy.ops));
+    if (pci_is_thunderbolt_attached(pdev) > +        msleep(600);

I believe it is a bit fragile. I would recommend here look for another 
indication instead of delay. Can we poll for a 'pci_channel_io_normal' 
state? (igc->pdev->error_state == pci_channel_io_normal)

Hi sasha,
In this situation, the error_state is always pci_channel_io_normal.

Ok.

The delay is necessary.

Refer to "627239-Intel® Ethernet Controller 
I225-MAC-Address-Passthrough-rev1.2"
section "3.5
  Timing Considerations":

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);?

"For hardware implementation,

when the operating system is already running, the MAC copy must happen 
not more than one

second after TBT link is established.
the I225 Windows driver prevents the operating

system from detecting the I225 for one second. This allows enough time 
for hardware to update the

MAC address."

Thanks sasha,
Aaron

quoted

quoted

+
      /* Initialize skew-specific constants */
      err = ei->get_invariants(hw);
      if (err)

Thanks Aaron,
sasha

Sasha