[REGRESSION] mainline/master: PCI link creation fails on Apalis iMX6

[REGRESSION] mainline/master: PCI link creation fails on Apalis iMX6

[Leonardo Costa]

Hello,

We are seeing a regression on Apalis iMX6 where connected PCI device
links fail to come up at initialization, as shown below. The issue is
not on the devices' physical connection, as they worked properly on v7.1
and are working on other stable kernel versions.

    [    0.154243] imx6q-pcie 1ffc000.pcie: host bridge /soc/pcie@1ffc000 ranges:
    [    0.154400] imx6q-pcie 1ffc000.pcie:       IO 0x0001f80000..0x0001f8ffff -> 0x0000000000
    [    0.154439] imx6q-pcie 1ffc000.pcie:      MEM 0x0001000000..0x0001efffff -> 0x0001000000
    [    0.154553] imx6q-pcie 1ffc000.pcie: config reg[1] 0x01f00000 == cpu 0x01f00000
    [    0.356072] imx6q-pcie 1ffc000.pcie: iATU: unroll F, 4 ob, 4 ib, align 64K, limit 4G
    [    0.356181] imx6q-pcie 1ffc000.pcie: Link: Only Gen1 is enabled
    [    1.364757] imx6q-pcie 1ffc000.pcie: Link failed to come up. LTSSM: POLL_CONFIG
    [    1.365056] imx6q-pcie 1ffc000.pcie: probe with driver imx6q-pcie failed with error -110

Complete logs: https://paste.debian.net/hidden/f08cdf68

This may have been caused by commit [1], which was introduced to solve
an issue where the Apalis iMX6 module wasn't booting, and this second
regression went unnoticed since then.

Is it possible for all PCI changes to be reverted back to how they were
in v7.1 before the next release?

[1] 7678e81498e2 ("PCI: imx6: Fix i.MX6Q/DL boot hang caused by improper PHY power sequencing")
Link: https://lore.kernel.org/all/20260629143439.361560-1-leoreis.costa@gmail.com/

Re: [REGRESSION] mainline/master: PCI link creation fails on Apalis iMX6

[Francesco Dolcini]

Hello all,


On Mon, Aug 10, 2026 at 02:54:45PM -0300, Leonardo Costa wrote:
> We are seeing a regression on Apalis iMX6 where connected PCI device
> links fail to come up at initialization, as shown below. The issue is
> not on the devices' physical connection, as they worked properly on v7.1
> and are working on other stable kernel versions.

just to make this more clear.

610fa91d9863 ("PCI: imx6: Assert PERST# before enabling regulators")
introduced a regression that prevented the boot. because of that we were
not able to run any of our test in our CI/CD

commit 7678e81498e2 ("PCI: imx6: Fix i.MX6Q/DL boot hang caused by improper PHY power sequencing")
fixes the boot issue, but now PCIe is not longer working


Francesco

Re: [REGRESSION] mainline/master: PCI link creation fails on Apalis iMX6

[Bjorn Helgaas]

[+cc Sherry]

On Mon, Aug 10, 2026 at 02:54:45PM -0300, Leonardo Costa wrote:
> Hello,
> 
> We are seeing a regression on Apalis iMX6 where connected PCI device
> links fail to come up at initialization, as shown below. The issue is
> not on the devices' physical connection, as they worked properly on v7.1
> and are working on other stable kernel versions.
> 
>     [    0.154243] imx6q-pcie 1ffc000.pcie: host bridge /soc/pcie@1ffc000 ranges:
>     [    0.154400] imx6q-pcie 1ffc000.pcie:       IO 0x0001f80000..0x0001f8ffff -> 0x0000000000
>     [    0.154439] imx6q-pcie 1ffc000.pcie:      MEM 0x0001000000..0x0001efffff -> 0x0001000000
>     [    0.154553] imx6q-pcie 1ffc000.pcie: config reg[1] 0x01f00000 == cpu 0x01f00000
>     [    0.356072] imx6q-pcie 1ffc000.pcie: iATU: unroll F, 4 ob, 4 ib, align 64K, limit 4G
>     [    0.356181] imx6q-pcie 1ffc000.pcie: Link: Only Gen1 is enabled
>     [    1.364757] imx6q-pcie 1ffc000.pcie: Link failed to come up. LTSSM: POLL_CONFIG
>     [    1.365056] imx6q-pcie 1ffc000.pcie: probe with driver imx6q-pcie failed with error -110
> 
> Complete logs: https://paste.debian.net/hidden/f08cdf68
> 
> This may have been caused by commit [1], which was introduced to solve
> an issue where the Apalis iMX6 module wasn't booting, and this second
> regression went unnoticed since then.
> 
> Is it possible for all PCI changes to be reverted back to how they were
> in v7.1 before the next release?

It's *possible*, but it's tight and it would be a lot to revert.  I
think all these have been added since v7.1:

  aad953fb4eed ("PCI: imx6: Fix IMX6SX_GPR12_PCIE_TEST_POWERDOWN handling")
  610fa91d9863 ("PCI: imx6: Assert PERST# before enabling regulators")
  250eea5c06f5 ("PCI: imx6: Parse 'reset-gpios' in Root Port nodes")
  0c26b1c34d12 ("PCI: imx6: Configure REF_USE_PAD before PHY reset for i.MX95")
  9dda3f83ba67 ("PCI: imx6: Assert ref_clk_en after reference clock stabilizes on i.MX95")
  85c1fcfa740d ("PCI: imx6: Integrate new pwrctrl API")
  d4b52f83f198 ("of: Add convenience wrappers for of_map_id()")
  f71f07bee9b5 ("of: Factor arguments passed to of_map_id() into a struct")
  3567bcf0e985 ("PCI: host-generic: Move legacy DT binding fallback decision to caller of pci_host_common_parse_ports()")
  2c5768344f88 ("PCI: imx6: Move pci_pwrctrl_create_devices() to imx_pcie_probe()")
  f26b1c697a2b ("PCI: imx6: Add 'skip_pwrctrl_off' flag support")
  c2b9620359b7 ("PCI: imx6: Add runtime PM support for i.MX95")
  7678e81498e2 ("PCI: imx6: Fix i.MX6Q/DL boot hang caused by improper PHY power sequencing")

I'm hoping Richard and Sherry can resolve this issue.  I guess maybe
the config details needed to reproduce it are in
https://lore.kernel.org/all/20260811063752.GA7332@francesco-nb ?

> [1] 7678e81498e2 ("PCI: imx6: Fix i.MX6Q/DL boot hang caused by improper PHY power sequencing")
> Link: https://lore.kernel.org/all/20260629143439.361560-1-leoreis.costa@gmail.com/