RE: [PATCH v1] PCI: imx6: Move clock enable after core reset assertion

[Hongxing Zhu (OSS)]

NXP Confidential
> -----Original Message-----
> From: Francesco Dolcini <francesco@xxxxxxxxxx>
> Sent: Thursday, August 13, 2026 4:39 PM
> To: Hongxing Zhu (OSS) <hongxing.zhu@xxxxxxxxxxx>
> Cc: leoreis.costa@xxxxxxxxx; fra.schnyder@xxxxxxxxx; francesco@xxxxxxxxxx;
> Frank Li <frank.li@xxxxxxx>; l.stach@xxxxxxxxxxxxxx; lpieralisi@xxxxxxxxxx;
> kwilczynski@xxxxxxxxxx; mani@xxxxxxxxxx; robh@xxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> festevam@xxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> Hongxing Zhu <hongxing.zhu@xxxxxxx>; stable@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v1] PCI: imx6: Move clock enable after core reset assertion
>
> On Thu, Aug 13, 2026 at 04:29:00PM +0800, hongxing.zhu@xxxxxxxxxxx wrote:
> > From: Richard Zhu <hongxing.zhu@xxxxxxx>
> >
> > Commit 610fa91d9863 ("PCI: imx6: Assert PERST# before enabling
> > regulators") inadvertently moved clock enablement before core reset
> > assertion, breaking PCI device initialization on i.MX6Q Apalis
> > platforms when
> > ASM1061/ASM1062 is connected.
> >
> > Logs:
> > root@apalis-imx6-11486042:~# dmesg | grep pcie imx6q-pcie
> > 1ffc000.pcie: host bridge /soc/pcie@1ffc000 ranges:
> > imx6q-pcie 1ffc000.pcie:       IO 0x0001f80000..0x0001f8ffff -> 0x0000000000
> > imx6q-pcie 1ffc000.pcie:      MEM 0x0001000000..0x0001efffff ->
> 0x0001000000
> > imx6q-pcie 1ffc000.pcie: config reg[1] 0x01f00000 == cpu 0x01f00000
> > imx6q-pcie 1ffc000.pcie: iATU: unroll F, 4 ob, 4 ib, align 64K, limit
> > 4G imx6q-pcie 1ffc000.pcie: Link: Only Gen1 is enabled imx6q-pcie
> > 1ffc000.pcie: Link failed to come up. LTSSM: POLL_CONFIG imx6q-pcie
> > 1ffc000.pcie: probe with driver imx6q-pcie failed with error -110
> >
> > To fix this regression, restore the original sequence where clocks are
> > enabled after asserting core reset and configuring the controller type.
> >
> > Fixes: 610fa91d9863 ("PCI: imx6: Assert PERST# before enabling
> > regulators")
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > Reported-by: Leonardo Costa <leoreis.costa@xxxxxxxxx>
> > Closes:
> > https://lore.kernel.org/all/bl7i3obu2clzsgeoct2a4mtfhv6typcjdqmgneropf
> > 3hpgwve6@n2m5uhlduw57/T/#u
> > Reported-by: Franz Schnyder <fra.schnyder@xxxxxxxxx>
> > Closes:
> > https://lore.kernel.org/all/t65y5d54axtksbfs7r4olcefqhwm6m4dz3njgnrnf7
> > fcotj74i@o7avoznlafbj/
> > Cc: stable@xxxxxxxxxxxxxxx # 7.1+
>
> 7.2+, 7.1 does not have the broken commit
>
> minor: it is not 100% clear if the issue is specific to the ASM1061/ASM1062
> device or on the specific power-up sequence (reset vs cold-power-on).
Thanks for your review comments.
Okay, I add this "minor" into commit message.

Richard Zhu
>
> Francesco