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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginatorOrg: sct-15-20-9412-4-msonline-outlook-d3deb.templateTenant X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: AS2PR10MB7429.EURPRD10.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: 6faf03d1-0c97-43e4-74a0-08df16ef46e4 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Sep 2026 08:15:05.1695 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB8PR10MB3691 Another reproducible case of the active-link failure described in this thre= ad.=0A= =0A= Hardware:=0A= Intel 4th-gen/9-series platform=0A= Intel 82571EB quad-port NIC=0A= Microsemi/PMC/IDT PES12N3A PCIe switch=0A= Root port 00:1c.4, LnkCap 5GT/s x4=0A= Working negotiated link: 2.5GT/s x4=0A= =0A= Kernel results:=0A= 7.2-rc1 fail=0A= 7.1-rc7 succes=0A= =0A= On failing kernels, the PES12N3A hierarchy does not enumerate and all four = downstream 82571EB ports disappear.=0A= =0A= I traced this to pcie_failed_link_retrain() and specifically the new generi= c clamp-removal code introduced by 72780f7964684939d7d2f69c348876213b184484= ("PCI: Always lift 2.5GT/s restriction in PCIe failed link retraining").= =0A= =0A= I tested 7.3.0-rc3+ with only this block commented out:=0A= =0A= pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2);=0A= if ((lnkctl2 & PCI_EXP_LNKCTL2_TLS) =3D=3D PCI_EXP_LNKCTL2_TLS_2_5GT) {= =0A= pci_info(dev, "removing 2.5GT/s downstream link speed restricti= on\n");=0A= ret =3D pcie_set_target_speed(dev, speed_cap, false);=0A= if (ret)=0A= goto err;=0A= }=0A= =0A= With that block disabled, 7.3.0-rc3+ boots normally, having all four NIC po= rts enumerate:=0A= =0A= 07:00.0 82571EB=0A= 07:00.1 82571EB=0A= 08:00.0 82571EB=0A= 08:00.1 82571EB=0A= =0A= The important result is that the initial 2.5GT/s recovery is fine. Leaving = the link at 2.5GT/s works. It is the subsequent:=0A= =0A= pcie_set_target_speed(dev, speed_cap, false);=0A= =0A= which breaks this PES12N3A/82571EB link.=0A= =0A= So this appears to be the same active-link failure mode, but with a PES12N3= A switch rather than a direct 82571EB connection.=0A= =0A= This was tested against vanilla 7.3.0-rc3+ with only the above local change= .=0A= =0A= I can provide full dmesg/lspci output and test a proposed fix if useful.=