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Rozycki" Cc: Bjorn Helgaas , Andreas Wild , linux-pci@vger.kernel.org, Bjorn Helgaas , linux-kernel@vger.kernel.org, M M , regressions@lists.linux.dev, blaat windows References: <20260917233355.GA1115024@bhelgaas> From: Thorsten Leemhuis Content-Language: de-DE, en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-PPP-Message-ID: <178998681509.217018.8059272518562419775@mxe9fb.netcup.net> X-Rspamd-Server: rspamd-worker-8404 X-Rspamd-Queue-Id: A7D775FC31 X-NC-CID: FUpWLpRNalb8yuhbPZz+iPk/MR3311IHVxmP+iUcn5PvMG0xI6U= On 9/18/26 12:39, Maciej W. Rozycki wrote: > On Fri, 18 Sep 2026, Thorsten Leemhuis wrote: > >>> But IIUC Aoxtj still sees issues with 72780f796468 ("PCI: Always lift >>> 2.5GT/s restriction in PCIe failed link retraining") even with this >>> patch >>> (https://lore.kernel.org/all/331e97c7-e422-420d-9f3e-5d9f734464b3@axtjblog.cc) >>> >>> And M M / Mich (BCC'd) also reports an issue that (IIUC) is not fixed by >>> this patch (https://bugzilla.kernel.org/show_bug.cgi?id=221919#c3) >>> >>> So evidently there are still issues but maybe this patch fixes part of >>> them? >>>> Yeah, Maciej ten days expressed that we to look into this. Anyway, I >> suggest someone that is affected by that problem starts a new thread >> (please CC all those that are affected by it and the regression list) >> with summarizing the current state + this patch, as this thread got a >> bit confusing... (please drop a link to that thread here afterwards) > > It remains on my radar, no worries. [...] FWIW, another report from "blaat windows" (now CCed) can be found out-of-thread here: https://lore.kernel.org/all/AS2PR10MB7429335B6C8F4C7FA3F88638B5852@AS2PR10MB7429.EURPRD10.PROD.OUTLOOK.COM/ Quoting that below. """ >>>> Another reproducible case of the active-link failure described in this thread. >>>> >>>> Hardware: >>>> Intel 4th-gen/9-series platform >>>> Intel 82571EB quad-port NIC >>>> Microsemi/PMC/IDT PES12N3A PCIe switch >>>> Root port 00:1c.4, LnkCap 5GT/s x4 >>>> Working negotiated link: 2.5GT/s x4 >>>> >>>> Kernel results: >>>> 7.2-rc1 fail >>>> 7.1-rc7 succes >>>> >>>> On failing kernels, the PES12N3A hierarchy does not enumerate and all four downstream 82571EB ports disappear. >>>> >>>> I traced this to pcie_failed_link_retrain() and specifically the new generic clamp-removal code introduced by 72780f7964684939d7d2f69c348876213b184484 ("PCI: Always lift 2.5GT/s restriction in PCIe failed link retraining"). >>>> >>>> I tested 7.3.0-rc3+ with only this block commented out: >>>> >>>> pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2); >>>> if ((lnkctl2 & PCI_EXP_LNKCTL2_TLS) == PCI_EXP_LNKCTL2_TLS_2_5GT) { >>>> pci_info(dev, "removing 2.5GT/s downstream link speed restriction\n"); >>>> ret = pcie_set_target_speed(dev, speed_cap, false); >>>> if (ret) >>>> goto err; >>>> } >>>> >>>> With that block disabled, 7.3.0-rc3+ boots normally, having all four NIC ports enumerate: >>>> >>>> 07:00.0 82571EB >>>> 07:00.1 82571EB >>>> 08:00.0 82571EB >>>> 08:00.1 82571EB >>>> >>>> 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: >>>> >>>> pcie_set_target_speed(dev, speed_cap, false); >>>> >>>> which breaks this PES12N3A/82571EB link. >>>> >>>> So this appears to be the same active-link failure mode, but with a PES12N3A switch rather than a direct 82571EB connection. >>>> >>>> This was tested against vanilla 7.3.0-rc3+ with only the above local change. >>>> >>>> I can provide full dmesg/lspci output and test a proposed fix if useful. """ Ciao, Thorsten