linux-kernel - Re: [PATCH v2 0/2] PCI/ASPM: Enable ASPM and Clock PM by default on devicetree platforms

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Message-ID: <4cp5pzmlkkht2ni7us6p3edidnk25l45xrp6w3fxguqcvhq2id@wjqqrdpkypkf>
Date: Sat, 8 Nov 2025 18:18:03 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: manivannan.sadhasivam@....qualcomm.com,
        Rob Clark <robin.clark@....qualcomm.com>,
        Vignesh Raman <vignesh.raman@...labora.com>,
        Valentine Burley <valentine.burley@...labora.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kwilczynski@...nel.org>,
        Rob Herring <robh@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        "David E. Box" <david.e.box@...ux.intel.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Chia-Lin Kao <acelan.kao@...onical.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH v2 0/2] PCI/ASPM: Enable ASPM and Clock PM by default on
 devicetree platforms

On Mon, Sep 22, 2025 at 09:46:43PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> Hi,
> 
> This series is one of the 'let's bite the bullet' kind, where we have decided to
> enable all ASPM and Clock PM states by default on devicetree platforms [1]. The
> reason why devicetree platforms were chosen because, it will be of minimal
> impact compared to the ACPI platforms. So seemed ideal to test the waters.
> 
> This series is tested on Lenovo Thinkpad T14s based on Snapdragon X1 SoC. All
> supported ASPM states are getting enabled for both the NVMe and WLAN devices by
> default.
> 
> [1] https://lore.kernel.org/linux-pci/a47sg5ahflhvzyzqnfxvpk3dw4clkhqlhznjxzwqpf4nyjx5dk@bcghz5o6zolk
> [2] https://lore.kernel.org/linux-pci/20250828204345.GA958461@bhelgaas
> 
> Changes in v2:
> 
> - Used of_have_populated_dt() instead of CONFIG_OF to identify devicetree
>   platforms
> - Renamed the override helpers and changed the override print
> - Moved setting the default state back to the original place and only kept the
>   override in helpers

The series breaks the DRM CI on DB820C board (apq8096, PCIe network
card, NFS root). The board resets randomly after some time ([1]).

Note:

- Reverting just the second patch is not enough ([2])

- Reverting the second patch and picking up df5192d9bb0e ("PCI/ASPM:
  Enable only L0s and L1 for devicetree platforms") is also nout enough
  ([3])

- Only revert of both patches results in a working pipeline ([4])


[1] https://gitlab.freedesktop.org/drm/msm/-/jobs/87321332

[2] https://gitlab.freedesktop.org/drm/msm/-/jobs/87476851

[3] https://gitlab.freedesktop.org/drm/msm/-/jobs/87482677

[4] https://gitlab.freedesktop.org/drm/msm/-/jobs/87481381

> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
> Manivannan Sadhasivam (2):
>       PCI/ASPM: Override the ASPM and Clock PM states set by BIOS for devicetree platforms
>       PCI: qcom: Remove the custom ASPM enablement code
> 
>  drivers/pci/controller/dwc/pcie-qcom.c | 32 --------------------------
>  drivers/pci/pcie/aspm.c                | 42 ++++++++++++++++++++++++++++++++--
>  2 files changed, 40 insertions(+), 34 deletions(-)
> ---
> base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
> change-id: 20250916-pci-dt-aspm-8b3a7e8d2cf1
> 
> Best regards,
> -- 
> Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> 
> 

-- 
With best wishes
Dmitry