[PATCH net-next v3 4/8] Documentation: networking: update PHY error counter diagnostics in twisted pair guide
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2024-12-20 13:09:03
Also in:
linux-doc, lkml
Subsystem:
documentation, networking [general], the rest · Maintainers:
Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Replace generic instructions for monitoring error counters with a procedure using the unified PHY statistics interface (`--all-groups`). Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- .../twisted_pair_layer1_diagnostics.rst | 39 +++++++++++++------ 1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/Documentation/networking/diagnostic/twisted_pair_layer1_diagnostics.rst b/Documentation/networking/diagnostic/twisted_pair_layer1_diagnostics.rst
index c9be5cc7e113..079e17effadf 100644
--- a/Documentation/networking/diagnostic/twisted_pair_layer1_diagnostics.rst
+++ b/Documentation/networking/diagnostic/twisted_pair_layer1_diagnostics.rst@@ -713,17 +713,23 @@ driver supports reporting such events. - **Monitor Error Counters**: - - While some NIC drivers and PHYs provide error counters, there is no unified - set of PHY-specific counters across all hardware. Additionally, not all - PHYs provide useful information related to errors like CRC errors, frame - drops, or link flaps. Therefore, this step is dependent on the specific - hardware and driver support. - - - **Next Steps**: Use `ethtool -S <interface>` to check if your driver - provides useful error counters. In some cases, counters may provide - information about errors like link flaps or physical layer problems (e.g., - excessive CRC errors), but results can vary significantly depending on the - PHY. + - Use `ethtool -S <interface> --all-groups` to retrieve standardized interface + statistics if the driver supports the unified interface: + + - **Command:** `ethtool -S <interface> --all-groups` + + - **Example Output (if supported)**: + + .. code-block:: bash + + phydev-RxFrames: 100391 + phydev-RxErrors: 0 + phydev-TxFrames: 9 + phydev-TxErrors: 0 + + - If the unified interface is not supported, use `ethtool -S <interface>` to + retrieve MAC and PHY counters. Note that non-standardized PHY counter names + vary by driver and must be interpreted accordingly: - **Command:** `ethtool -S <interface>`
@@ -740,6 +746,17 @@ driver supports reporting such events. condition) or kernel log messages (e.g., link up/down events) to further diagnose the issue. + - **Compare Counters**: + + - Compare the egress and ingress frame counts reported by the PHY and MAC. + + - A small difference may occur due to sampling rate differences between the + MAC and PHY drivers, or if the PHY and MAC are not always fully + synchronized in their UP or DOWN states. + + - Significant discrepancies indicate potential issues in the data path + between the MAC and PHY. + When All Else Fails... ~~~~~~~~~~~~~~~~~~~~~~
--
2.39.5