linux-kernel - Re: [PATCH v3 0/4] PCI: dwc: Rework the error handling of dw_pcie_wait_for

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Message-ID: <aW-SpCEPSakHAJ0B@ryzen>
Date: Tue, 20 Jan 2026 15:35:16 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: manivannan.sadhasivam@....qualcomm.com,
	Jingoo Han <jingoohan1@...il.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	vincent.guittot@...aro.org, zhangsenchuan@...incomputing.com,
	Shawn Lin <shawn.lin@...k-chips.com>, dlemoal@...nel.org
Subject: Re: [PATCH v3 0/4] PCI: dwc: Rework the error handling of
 dw_pcie_wait_for_link() API

On Fri, Jan 16, 2026 at 02:27:39PM +0530, Manivannan Sadhasivam wrote:

(snip)

> > So I don't think that setting the DIRECT_POLCOMP_TO_DETECT bit will
> > help us PCIe endpoint developers to continue with the workflow where we
> > can simply do a rescan on the host after starting the link training on
> > the EP.
> >
> > Back to finding another alternative. Kconfig? module param? Suggestions?
> > 
> 
> I don't like the user to control this behavior as it is just how the link
> behaves. Maybe we can allow the link to stay in POLL and print out a different
> message, and still return -ENODEV? Like,
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index c2dfadc53d04..21ce206f359b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -774,6 +774,14 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
>                     ltssm == DW_PCIE_LTSSM_DETECT_ACT) {
>                         dev_info(pci->dev, "Device not found\n");
>                         return -ENODEV;
> +               /*
> +                * If the link is in POLL.Compliance state, then the device is
> +                * found to be connected to the bus, but it is not active i.e.,
> +                * the device firmware might not yet initialized.
> +                */
> +               } else if (ltssm == DW_PCIE_LTSSM_POLL_COMPLIANCE) {
> +                       dev_info(pci->dev, "Device found, but not active\n");
> +                       return -ENODEV;
>                 }
>  
>                 dev_err(pci->dev, "Link failed to come up. LTSSM: %s\n",


Seems like an excellent idea to me!

I tested it, and it works, thank you.


Kind regards,
Niklas