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

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Message-ID: <CAKfTPtDgbkH57bahUAee8_N3QYWNuu6-jZFrJH1GW32aMiZ+og@mail.gmail.com>
Date: Mon, 5 Jan 2026 11:04:21 +0100
From: Vincent Guittot <vincent.guittot@...aro.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, zhangsenchuan@...incomputing.com, 
	Shawn Lin <shawn.lin@...k-chips.com>
Subject: Re: [PATCH v3 0/4] PCI: dwc: Rework the error handling of
 dw_pcie_wait_for_link() API

On Tue, 30 Dec 2025 at 16:07, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org> wrote:
>
> Hi,
>
> This series reworks the dw_pcie_wait_for_link() API to allow the callers to
> detect the absence of the device on the bus and skip the failure.
>
> Compared to v2, I've reworked the patch 2 to improve the API further and
> dropped the patch 1 that got applied (hence changed the subject). I've also
> modified the error code based on the feedback in v2 to return -ENODEV if device
> is not detected on the bus and -ETIMEDOUT otherwise. This allows the callers to
> skip the failure if device is not detected and handle error for other failure.
>
> Testing
> =======
>
> Tested this series on Rb3Gen2 board without powering on the PCIe switch. Now the
> dw_pcie_wait_for_link() API prints:
>
>         qcom-pcie 1c08000.pcie: Device not found
>
> Instead of the previous log:
>
>         qcom-pcie 1c08000.pcie: Phy link never came up

I tested the patchset with s32g399a-rdb3 and during the resume, I have:

[  460.255927] s32g-pcie 44100000.pcie: Device not found
[  460.256021] s32g-pcie 44100000.pcie: PM: dpm_run_callback():
s32g_pcie_resume_noirq returns -19
[  460.256278] s32g-pcie 44100000.pcie: PM: failed to resume noirq: error -19

I was not expecting more lines than the 1st line: Device not found,
like the init

[    2.668921] s32g-pcie 44100000.pcie: Device not found
[    2.675342] s32g-pcie 44100000.pcie: PCI host bridge to bus 0001:00

where with skip the -ENODEV case if dw_pcie_wait_for_link() fails

Should we skip the -ENODEV case in dw_pcie_resume_noirq() too ?

>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
> Changes in v3:
> - Dropped patch 1 that got appplied
> - Reworked the error handling of dw_pcie_wait_for_link() API further
> - Link to v2: https://lore.kernel.org/r/20251218-pci-dwc-suspend-rework-v2-0-5a7778c6094a@oss.qualcomm.com
>
> Changes in v2:
> - Changed the logic to check for Detect.Quiet/Active states
> - Collected tags and rebased on top of v6.19-rc1
> - Link to v1: https://lore.kernel.org/r/20251119-pci-dwc-suspend-rework-v1-0-aad104828562@oss.qualcomm.com
>
> ---
> Manivannan Sadhasivam (4):
>       PCI: dwc: Return -ENODEV from dw_pcie_wait_for_link() if device is not found
>       PCI: dwc: Rename and move ltssm_status_string() to pcie-designware.c
>       PCI: dwc: Rework the error print of dw_pcie_wait_for_link()
>       PCI: dwc: Only skip the dw_pcie_wait_for_link() failure if it returns -ENODEV
>
>  .../pci/controller/dwc/pcie-designware-debugfs.c   | 54 +---------------
>  drivers/pci/controller/dwc/pcie-designware-host.c  |  6 +-
>  drivers/pci/controller/dwc/pcie-designware.c       | 75 +++++++++++++++++++++-
>  drivers/pci/controller/dwc/pcie-designware.h       |  2 +
>  4 files changed, 80 insertions(+), 57 deletions(-)
> ---
> base-commit: 68ac85fb42cfeb081cf029acdd8aace55ed375a2
> change-id: 20251119-pci-dwc-suspend-rework-8b0515a38679
>
> Best regards,
> --
> Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
>
>