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Tue, 3 Mar 2026 13:38:13 +0100 (CET) From: Alexander Stein To: linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, Richard Zhu Subject: i.MX8M Plus PCIe link regression Date: Tue, 03 Mar 2026 13:38:13 +0100 Message-ID: <23024521.EfDdHjke4D@steina-w> Organization: TQ-Systems GmbH Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" X-cloud-security-sender:alexander.stein@ew.tq-group.com X-cloud-security-recipient:imx@lists.linux.dev X-cloud-security-crypt: load encryption module X-cloud-security-Mailarchiv: E-Mail archived for: alexander.stein@ew.tq-group.com X-cloud-security-Mailarchivtype:outbound X-cloud-security-Virusscan:CLEAN X-cloud-security-disclaimer: This E-Mail was scanned by E-Mailservice on mx-relay100-hz2.antispameurope.com with 4fQFhP74nLz3PJhp X-cloud-security-connect: he-nlb01-hz1.hornetsecurity.com[94.100.132.6], TLS=1, IP=94.100.132.6 X-cloud-security-Digest:850274fae2b2e7370f7fd9100b832d79 X-cloud-security:scantime:1.471 DKIM-Signature: a=rsa-sha256; bh=lWwoqo46Zr/3jyyKrQqeEXquRAWf+PTNX5MMsSlQxIA=; c=relaxed/relaxed; d=ew.tq-group.com; h=content-type:mime-version:subject:from:to:message-id:date; s=hse1; t=1772541497; v=1; b=YvAbcta7MZpA5HWATbnZBhbYpsjOODCPLNzdo+TXhw8yUQbOeEd2IbU8w8M9bpZpbKrmszY0 LRVYDTf/ruZ4wQOo77lwCBMwLnJSB0FV1uR34kVOsrN2P62nXTUd2S+pb+h/IrhaKl7VqUigZVB fciCnRUCMy4HxbRSGoU0MuiuGVDqi/x+S79rOE5USveyRZ4cMT6dTKcdpY1c8cIEt2aMkMdY+Qt 30wJ8aYOVlG0bXY+WWuzAdLsqzC30pbD467LXS9g4d9VFdzjWE7/LVUygxlua3l3Mez7TWw20Ey Sd/Uwt2J7XK2VOkhKNWASmrtMYziQq85QEHae1kXthfhw== Hi, these days I noticed that there is a PCIe link regression on my i.MX8MP platform (TQMa8MPxL) running next-20260227. I could bisect it back to commit 9c03e30e3ade3 ("PCI: imx6: Skip link up=20 workaround for newer platforms"). I always get the following errors: imx6q-pcie 33800000.pcie: Link failed to come up. LTSSM: CFG_LINKWD_START imx6q-pcie 33800000.pcie: probe with driver imx6q-pcie failed with error -1= 10 Connected is a Gen1 PCIe -> Ethernet adapter. Interestingly a Gen2 device is detected without issues. Reverting 3c96a61dd2e098dda8dcac3dce3d38a3c87afbfc and b9a8d28ebbf118bb3eac953f4a37abbd341257ab "fixes" my platform, both Gen 1 and Gen 2 devices are detect. Commit 3c96a61dd2e098dda8dcac3dce3d38a3c87afbfc i= s only required for conflict free revert. Here is a summary with outputs: Gen 1 device > 00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01) > 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. > RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 01) Gen 2 device > 00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01) > 01:00.0 SATA controller: Marvell Technology Group Ltd. 88SE9128 PCIe SATA= 6 > Gb/s RAID controller (rev 20) output of "dmesg | grep imx6q-pcie". Common part for all tests: > imx6q-pcie 33800000.pcie: host bridge /soc@0/pcie@33800000 ranges: > imx6q-pcie 33800000.pcie: IO 0x001ff80000..0x001ff8ffff -> > 0x0000000000 > imx6q-pcie 33800000.pcie: MEM 0x0018000000..0x001fefffff -> > 0x0018000000 > imx6q-pcie 33800000.pcie: config reg[1] 0x1ff00000 =3D=3D cpu 0x1ff00000 > imx6q-pcie 33800000.pcie: iATU: unroll T, 4 ob, 4 ib, align 64K, limit 16G next-20260227 Gen 1 > imx6q-pcie 33800000.pcie: Link failed to come up. LTSSM: CFG_LINKWD_START > imx6q-pcie 33800000.pcie: probe with driver imx6q-pcie failed with error = =2D110 Gen 2 > imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up > imx6q-pcie 33800000.pcie: PCI host bridge to bus 0000:00 next-20260227 + reverts Gen 1 > imx6q-pcie 33800000.pcie: PCIe Gen.1 x1 link up > imx6q-pcie 33800000.pcie: PCIe Gen.1 x1 link up > imx6q-pcie 33800000.pcie: PCI host bridge to bus 0000:00 Gen 2 > imx6q-pcie 33800000.pcie: PCIe Gen.1 x1 link up > imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up > imx6q-pcie 33800000.pcie: PCI host bridge to bus 0000:00 What can we do here? I'm wondering why Gen 2 trains correctly, while Gen 1 doesn't. Best regards, Alexander =2D-=20 TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/