linux-kernel - Re: [PATCH v4 2/5] PCI: dwc: Return -EIO from dw_pcie_wait_for

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Message-ID: <aXCM-ky9PFTKZTcZ@ryzen>
Date: Wed, 21 Jan 2026 09:23:22 +0100
From: Niklas Cassel <cassel@...nel.org>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Jingoo Han <jingoohan1@...il.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	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>,
	Richard Zhu <hongxing.zhu@....com>
Subject: Re: [PATCH v4 2/5] PCI: dwc: Return -EIO from
 dw_pcie_wait_for_link() if device is not active

On Tue, Jan 20, 2026 at 11:17:41PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> 
> There are cases where the PCIe device would be physically connected to the
> bus, but the device firmware might not be active. So the LTSSM will
> get stuck in POLL.{Active/Compliance} states.
> 
> This behavior is common with endpoint devices controlled by the PCI
> Endpoint framework, where the device will wait for the user to start its
> operation through configfs.
> 
> For those cases, print the relevant log and return -EIO to indicate that
> the device is present, but not active. This will allow the callers to skip
> the failure as the device might become active in the future.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 55c1c60f7f8f..aca5bbeade03 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -696,8 +696,9 @@ void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index)
>   * dw_pcie_wait_for_link - Wait for the PCIe link to be up
>   * @pci: DWC instance
>   *
> - * Returns: 0 if link is up, -ENODEV if device is not found, -ETIMEDOUT if the
> - * link fails to come up for other reasons.
> + * Returns: 0 if link is up, -ENODEV if device is not found, -EIO if the device
> + * is found but not active and -ETIMEDOUT if the link fails to come up for other
> + * reasons.
>   */
>  int dw_pcie_wait_for_link(struct dw_pcie *pci)
>  {
> @@ -722,6 +723,16 @@ 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.{Active/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_ACTIVE ||
> +			   ltssm == DW_PCIE_LTSSM_POLL_COMPLIANCE) {
> +			dev_info(pci->dev, "Device found, but not active\n");
> +			return -EIO;
>  		}
>  
>  		dev_info(pci->dev, "Phy link never came up\n");

This should probably be squashed with the previous patch.

Regardless:
Reviewed-by: Niklas Cassel <cassel@...nel.org>