RE: [PATCH v8 2/2] PCI: dwc: Don't return error when wait for link up in dw_pcie_resume_noirq()

[Hongxing Zhu]

> -----Original Message-----
> From: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> Sent: 2026年1月13日 23:30
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: Frank Li <frank.li@xxxxxxx>; jingoohan1@xxxxxxxxx;
> l.stach@xxxxxxxxxxxxxx; lpieralisi@xxxxxxxxxx; kwilczynski@xxxxxxxxxx;
> robh@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; shawnguo@xxxxxxxxxx;
> s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx;
> linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> imx@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v8 2/2] PCI: dwc: Don't return error when wait for link up
> in dw_pcie_resume_noirq()
>
> On Wed, Jan 07, 2026 at 10:45:53AM +0800, Richard Zhu wrote:
> > When waiting for the PCIe link to come up, both link up and link down
> > are valid results depending on the device state.
> >
> > Since the link may come up later and to get rid of the following
> > mis-reported PM errors. Do not return an -ETIMEDOUT error, as the
> > outcome has already been reported in dw_pcie_wait_for_link().
> >
> > PM error logs introduced by the -ETIMEDOUT error return.
> > imx6q-pcie 33800000.pcie: Phy link never came up imx6q-pcie
> > 33800000.pcie: PM: dpm_run_callback(): genpd_resume_noirq returns -110
> > imx6q-pcie 33800000.pcie: PM: failed to resume noirq: error -110
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 4774faf854f5 ("PCI: dwc: Implement generic suspend/resume
> > functionality")
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> > ---
> >  drivers/pci/controller/dwc/pcie-designware-host.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c
> > b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 06cbfd9e1f1e..025e11ebd571 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -1245,10 +1245,9 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
> >     if (ret)
> >             return ret;
> >
> > -   ret = dw_pcie_wait_for_link(pci);
> > -   if (ret)
> > -           return ret;
> > +   /* Ignore errors, the link may come up later */
> > +   dw_pcie_wait_for_link(pci);
>
> It is not safe to ignore failures during resume. Because, if a device gets
> removed during suspend, the link up error will be unnoticed. I've proposed a
> different logic in this series, which should address your issue:
> https://lore.kern/
> el.org%2Flinux-pci%2F20260107-pci-dwc-suspend-rework-v4-0-9b5f3c72df0a%
> 40oss.qualcomm.com%2F&data=05%7C02%7Chongxing.zhu%40nxp.com%7Cf8
> 79871f9d0445aa0a3c08de52b8a2c0%7C686ea1d3bc2b4c6fa92cd99c5c301635
> %7C0%7C0%7C639039150121991830%7CUnknown%7CTWFpbGZsb3d8eyJFbXB
> 0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbC
> IsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=PNdsT530dbRQkgYsrr99gB1cUE
> BLOkynvciC9tiB0Ic%3D&reserved=0
>
> Please test it out.
Hi Mani:
You're right.
Tested on i.MX platforms, no error return anymore. Only "Device not found" is
 dumped out when no endpoint device is connected. Thanks.
Tested-by: Richard Zhu <hongxing.zhu@xxxxxxx>

Best Regards
Richard Zhu
>
> - Mani
>
> --
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