Re: [PATCH v6 08/11] PCI: dwc: Invoke post_init in dw_pcie_resume_noirq()

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Oct 15, 2025 at 11:04:25AM +0800, Richard Zhu wrote:
> If the ops has post_init callback, invoke it in dw_pcie_resume_noirq().

I'm trying to write the merge commit log for this branch, and I don't
quite understand this.

The effect is to apply the GEN3_ZRXDC_NONCOMPL workaround for the
ERR051586 erratum, and Mani added the hint that this enables REFCLK
during resume.  But it seems weird that we apply a REFCLK workaround
after the link is already up.

During probe, .post_init() is run after pci_host_probe(), so we apply
the workaround after enumerating all the devices, which means REFCLK
must already be valid and the link is already up.

Is "enabling REFCLK" actually what imx_pcie_host_post_init() does?

Could the workaround be done in imx_pcie_host_init() before the link
is brought up?  If it could, it looks like we wouldn't need
imx_pcie_host_post_init() at all.

For now, I put this in the merge commit log:

  - Apply i.MX95 ERR051586 erratum workaround for REFCLK issue during
    resume (Richard Zhu)

> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 20c9333bcb1c4..2b59e7d2e6179 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -1199,6 +1199,9 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
>  	if (ret)
>  		return ret;
>  
> +	if (pci->pp.ops->post_init)
> +		pci->pp.ops->post_init(&pci->pp);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(dw_pcie_resume_noirq);
> -- 
> 2.37.1
>