From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DADB7313552; Wed, 11 Feb 2026 18:29:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770834550; cv=none; b=GP+NM0iVk5Ttn0D2UUQI57e7pXv72pctn3kzMOAnamm9sKk+/eeaQ4uH1sKPoVGOavWMYT+f/KM2Iu8rwxK4HnO0xLLaSXr8Hn0OOlJb37gZ8mfrThh4pytx3nxnLnoNn7/EYycg9CreZRSSSlxSEjaou6q6rTFCFUd6et5fa6Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770834550; c=relaxed/simple; bh=FkTdMrzfnWOa65M7TOxVOTewRFDuBbrSyTDkM7TTM8w=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=b8XNLretdvXyctEaIchimOOAtOtYBG+lgUnRpT61O7/1W2ClfeRrJ3zirBPNLN1wtFKvLrAPJZh4zDLl97gAIIvkCZ0GGrax7pi5HbByzFBstu1bX4XAWuZqU7yrW7A3f0ybkp9bsviy63PfSggMG/I+nkv4pXc2UqfE+N2M/M8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ihi46+2E; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ihi46+2E" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 507CFC4CEF7; Wed, 11 Feb 2026 18:29:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770834550; bh=FkTdMrzfnWOa65M7TOxVOTewRFDuBbrSyTDkM7TTM8w=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=ihi46+2ENQiAMifT2Lwhf/yFa/G83yY9BjSdarvUEs+XcVzxfI+w05QH04NLlMp0v 44hlBE/eE0wfizEO2hpc3uOb9+MU2yNXFctF3UZ14tUxQhcQdGA9ImtLD+ewuTLLcA 7Gms8XyrzbWAPve/KSNRv5/gHcsC/YWNMqzxlEAQrjNTP+Atlg3RmmhshTFiw+hwRY IGqizqdeHOJe4/B7D3oCPwH4+azvPI89LhaJmhtW97tIzFamykfTgd/rmPY/jw/SqF jWoxRbhpyre9gOys2dhtDuzF9RoTzddsb6XliZydSW2JA39prYpok2l+VRtNsIO3qE 9TUrdcrz+HFkw== Date: Wed, 11 Feb 2026 12:29:09 -0600 From: Bjorn Helgaas To: Harshank Matkar Cc: "intel-wired-lan@lists.osuosl.org" , "netdev@vger.kernel.org" , "tony.nguyen@intel.com" , "davem@davemloft.net" , "kuba@kernel.org" , "pabeni@redhat.com" , "edumazet@google.com" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] igc: Add PCIe link recovery for I225/I226 Message-ID: <20260211182909.GA117627@bhelgaas> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260210203332.23200-1-harshankmatkar1304@outlook.com> On Tue, Feb 10, 2026 at 08:34:02PM +0000, Harshank Matkar wrote: > From: Harshank Matkar > > When ASPM L0s transitions occur on Intel I225/I226 controllers, > transient PCIe link instability can cause register read failures > (0xFFFFFFFF responses). At the PCIe level, the failure is some uncorrectable PCIe error like a Completion Timeout or Unsupported Request. The 0xFFFFFFFF response is implementation-specific behavior determined by the Root Complex design. > Implement a multi-layer recovery strategy: > 1. Immediate retries: 3 attempts with 100-200μs delays > 2. Link retraining: Trigger PCIe link retraining via capabilities > 3. Device detachment: Only as last resort after max attempts > > The recovery mechanism includes rate limiting, maximum attempt > tracking, and device presence validation to prevent false detaches > on transient ASPM glitches while maintaining safety through > bounded retry limits. I assume the glitch is a hardware erratum and should be documented as such by Intel, although it's possible ASPM L0s isn't configured correctly. If it's a hardware erratum, I think you should use a quirk to disable L0s on these devices, e.g., pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S). Even if this patch allows recovery, the PCIe errors will be logged and reported via AER, which will be confusing to users. Bjorn