Re: [PATCH] PCI: qcom: Ignore -ENODEV after Root Port reset

[Niklas Cassel]

On Wed, Sep 16, 2026 at 06:13:29PM +0200, Konrad Dybcio wrote:
> On 9/16/26 5:53 PM, Niklas Cassel wrote:
> > Hello Konrad,
> > 
> > On Wed, Sep 16, 2026 at 02:37:49PM +0200, Konrad Dybcio wrote:
> >> Root Port recovery may race with a device hot-unplug. In that case,
> >> dw_pcie_wait_for_link() returns -ENODEV because no device is detected
> >> after the controller has been successfully reset.
> >>
> >> This is a valid outcome and should not cause Root Port recovery to
> >> fail. Ignore -ENODEV while continuing to propagate other link-training
> >> errors.
> >>
> >> Assisted-by: LLM
> >> Fixes: 4d88cb82a6d9 ("PCI: qcom: Implement .reset_root_port() and use for link down")
> >> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> >> ---
> >>  drivers/pci/controller/dwc/pcie-qcom.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> >> index ee63a6ec99de4d07c16b8d6cb68df0d92f822cd8..3d3be9bf798b7c247d69969d6570385b8648123f 100644
> >> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> >> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> >> @@ -1880,6 +1880,9 @@ static int qcom_pcie_reset_root_port(struct pci_host_bridge *bridge,
> >>  	qcom_pcie_start_link(pci);
> >>  
> >>  	ret = dw_pcie_wait_for_link(pci);
> >> +	/* This linkdown might have been a hot-unplug */
> >> +	if (ret == -ENODEV)
> >> +		ret = 0;
> >>  	if (ret)
> >>  		return ret;
> > 
> > 
> > I did not know that pcie-qcom supported hotplug.
> > 
> > Last when I was discussing this with Mani, I'm quite sure that he said that
> > it doesn't, see:
> > https://lore.kernel.org/all/20251222064207.3246632-8-cassel@xxxxxxxxxx/
> 
> I don't know if native ports still don't, but the ones used for USB4
> tunneling certainly do
> 
> see e.g.:
> 65ccb2203ef8 ("PCI: qcom: Clear Attention Button Present in Slot Capabilities")

Ok, nice to see :)


Kind regards,
Niklas