On Mon, 2026-06-22 at 15:26 +0000, Loktionov, Aleksandr wrote:

quoted

-----Original Message-----
From: Intel-wired-lan <redacted> On Behalf
Of Ding Meng via Intel-wired-lan
Sent: Monday, June 22, 2026 6:13 AM
To: Nguyen, Anthony L <anthony.l.nguyen@intel.com>; Kitszel,
Przemyslaw [off-list ref]; andrew+netdev@lunn.ch;
davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
pabeni@redhat.com; Kiszka, Jan [off-list ref]; Bezdeka,
Florian [off-list ref]
Cc: intel-wired-lan@lists.osuosl.org; linux-kernel@vger.kernel.org;
netdev@vger.kernel.org; meng.ding@siemens.com; wq.wang@siemens.com
Subject: [Intel-wired-lan] [PATCH net] igc: Fix RX HW timestamp
reporting when NET_RX_BUSY_POLL is disabled

When CONFIG_NET_RX_BUSY_POLL is deactivated, fetching RX HW timestamps
from the NIC no longer works as expected.

This occurs because disabling CONFIG_NET_RX_BUSY_POLL disables the SKB
NAPI mapping in __skb_mark_napi_id(). Consequently, get_timestamp()
fails to perform its driver lookup, and the igc driver's struct
net_device_ops::ndo_get_tstamp is never invoked.

Instead, get_timestamp() falls back to use shhwtstamps(skb)->hwtstamp,
a field that the driver has not populated.

Fix this by populating the hwtstamp field with the correct timestamp
in the default timer when CONFIG_NET_RX_BUSY_POLL is disabled.

Fixes: 069b142f5819 ("igc: Add support for PTP .getcyclesx64()")

I think, because it's a fix, it needs Cc: stable@vger.kernel.org

Once we hit mainline the stable machinery will pick it up by following
the Fixes: tag. If that fails for some reason we can ping stable
manually.

Florian

Reviewed-by: Aleksandr Loktionov <redacted>

quoted

Co-developed-by: Florian Bezdeka <redacted>
Signed-off-by: Florian Bezdeka <redacted>
Signed-off-by: Ding Meng <redacted>
---

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