linux-kernel - [PATCH 0/3] PCI: qcom: Add D3cold support

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Message-Id: <20260128-d3cold-v1-0-dd8f3f0ce824@oss.qualcomm.com>
Date: Wed, 28 Jan 2026 17:10:40 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: 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>,
        Will Deacon <will@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        jonathanh@...dia.com,
        Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: [PATCH 0/3] PCI: qcom: Add D3cold support

This series adds a common helper to determine when a PCIe host bridge
can safely enter D3cold, converts the DesignWare host driver to use that
helper, and enables D3cold support for Qualcomm PCIe controllers.

The first patch introduces pci_host_common_can_enter_d3cold() in
pci-host-common. The helper walks all devices on the bridge's bus and
only allows the host bridge to enter D3cold if all PCIe endpoints are
already in PCI_D3hot. For devices that may wake the system, it
additionally requires that the device support PME wakeup from D3cold
(via WAKE#). Devices without wakeup enabled are not restricted by this
check and may be left in D3cold.

The second patch updates the DesignWare host driver to use this common
helper in dw_pcie_suspend_noirq(). Previously, the driver skipped
putting the link into L2 / device D3cold whenever L1 ASPM was enabled,
since some devices (e.g. NVMe) expect low resume latency and may not
tolerate deeper power states. However, such devices typically remain in
D0 and are already covered by the helper's requirement that all
endpoints be in D3hot before the host bridge may enter D3cold. Using the
shared helper removes this coarse heuristic and centralizes the D3cold
eligibility policy.

The third patch enables D3cold support for Qualcomm PCIe controllers. It
adds pme_turn_off() support and switches to the DesignWare common
suspend/resume methods for device D3cold entry and exit. If the
controller is not kept in D3cold, the existing paths are used so that
ICC votes, OPP votes, and other resources remain managed as before. In
addition, qcom_pcie_deinit_2_7_0() is updated to explicitly disable
PCIe clocks and resets in the controller, and the now-unused "suspended"
flag is removed from struct qcom_pcie.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
Krishna Chaitanya Chundru (3):
      PCI: host-common: Add shared D3cold eligibility helper for host bridges
      PCI: dwc: Use common D3cold eligibility helper in suspend path
      PCI: qcom: Add D3cold support

 drivers/pci/controller/dwc/pcie-designware-host.c |   7 +-
 drivers/pci/controller/dwc/pcie-designware.h      |   1 +
 drivers/pci/controller/dwc/pcie-qcom.c            | 114 +++++++++++++---------
 drivers/pci/controller/pci-host-common.c          |  29 ++++++
 drivers/pci/controller/pci-host-common.h          |   2 +
 5 files changed, 101 insertions(+), 52 deletions(-)
---
base-commit: 590a64365d9bcc13ee644a3e73ffdc3df26cf23c
change-id: 20251229-d3cold-bf99921960bb

Best regards,
-- 
Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>