[{"id":3676644,"web_url":"http://patchwork.ozlabs.org/comment/3676644/","msgid":"<20260413105110.695930-2-horms@kernel.org>","list_archive_url":null,"date":"2026-04-13T10:51:11","subject":"Re: [Intel-wired-lan] [PATCH iwl-net v2 3/6] ixgbe: call\n ixgbe_setup_fc() before fc_enable() after NVM update","submitter":{"id":82748,"url":"http://patchwork.ozlabs.org/api/people/82748/","name":"Simon Horman","email":"horms@kernel.org"},"content":"From: 'Simon Horman' \n\nThis is an AI-generated review of your patch. The human sending this\nemail has considered the AI review valid, or at least plausible.\nFull review at: https://sashiko.dev\n---\nixgbe: call ixgbe_setup_fc() before fc_enable() after NVM update\n\nThis commit adds a call to hw->mac.ops.setup_fc() before fc_enable() in the\nwatchdog task when the link comes up, aiming to prevent MDD events after\nan NVM update by reprogramming flow-control autonegotiation.\n\n> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c\n> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c\n> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c\n> @@ -8031,7 +8031,14 @@ static void ixgbe_watchdog_update_link(struct ixgbe_adapter *adapter)\n> \t\tpfc_en |= !!(adapter->ixgbe_ieee_pfc->pfc_en);\n> \n> \tif (link_up && !((adapter->flags & IXGBE_FLAG_DCB_ENABLED) && pfc_en)) {\n> -\t\thw->mac.ops.fc_enable(hw);\n> +\t\t/* Re-program flow-control autoneg before applying the result.\n> +\t\t * If setup_fc() fails its output is invalid; skip fc_enable()\n> +\t\t * to avoid committing stale capability bits that trigger MDD.\n> +\t\t */\n> +\t\tif (hw->mac.ops.setup_fc && hw->mac.ops.setup_fc(hw))\n\nWill calling setup_fc() unconditionally from the link-up watchdog cause an\ninfinite link flapping loop on 82599 backplane interfaces?\n\nFor backplane interfaces like KX/KX4/KR, setup_fc() resolves to\nixgbe_setup_fc_generic(), which then calls hw->mac.ops.prot_autoc_write().\n\nOn 82599 hardware, this calls prot_autoc_write_82599(), which unconditionally\nexecutes ixgbe_reset_pipeline_82599().\n\nSince ixgbe_reset_pipeline_82599() toggles the IXGBE_AUTOC_AN_RESTART bit,\nwould this drop the link immediately to restart Auto-Negotiation?\n\nIf the link drops, it would trigger a link-down LSC interrupt. Once\nAuto-Negotiation completes, the link would come back up, triggering another\nlink-up LSC interrupt. This would cause ixgbe_watchdog_update_link() to run\nagain, repeating the cycle.\n\n> +\t\t\te_warn(drv, \"setup_fc failed, skipping fc_enable\\n\");\n> +\t\telse\n> +\t\t\thw->mac.ops.fc_enable(hw);\n> \t\tixgbe_set_rx_drop_en(adapter);\n> \t}","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","intel-wired-lan@lists.osuosl.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","intel-wired-lan@lists.osuosl.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=osuosl.org header.i=@osuosl.org header.a=rsa-sha256\n header.s=default header.b=pCksf7Ke;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=osuosl.org\n (client-ip=140.211.166.136; helo=smtp3.osuosl.org;\n envelope-from=intel-wired-lan-bounces@osuosl.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fvPNh4w3zz1yDF\n\tfor ; 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