linux-kernel - [PATCH v2 0/3] PM/OPP: Support to match OPP based on both frequency and level

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Message-Id: <20250818-opp_pcie-v2-0-071524d98967@oss.qualcomm.com>
Date: Mon, 18 Aug 2025 13:52:52 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        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>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org,
        Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: [PATCH v2 0/3] PM/OPP: Support to match OPP based on both
 frequency and level

The existing OPP table in the device tree for PCIe is shared across
different link configurations such as data rates 8GT/s x2 and 16GT/s x1.
These configurations often operate at the same frequency, allowing them
to reuse the same OPP entries. However, 8GT/s and 16 GT/s may have
different characteristics beyond frequency—such as RPMh votes in QCOM
case, which cannot be represented accurately when sharing a single OPP.

In such cases, frequency alone is not sufficient to uniquely identify
an OPP. To support these scenarios, introduce a new API
dev_pm_opp_find_freq_level_exact() that allows OPP lookup using both
frequency and performance level.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
Changes in v2:
- Use opp-level to indentify data rate and use both frequency and level
  to identify the OPP. (Viresh)
- Link to v1: https://lore.kernel.org/r/20250717-opp_pcie-v1-0-dde6f452571b@oss.qualcomm.com

---
Krishna Chaitanya Chundru (3):
      PM/OPP: Support to match OPP based on both frequency and level.
      arm64: dts: qcom: sm8450: Add opp-level to indicate PCIe data rates
      PCI: qcom: Use frequency and level based OPP lookup

 arch/arm64/boot/dts/qcom/sm8450.dtsi   |  41 ++++++++++---
 drivers/opp/core.c                     | 103 +++++++++++++++++++++++++++++++++
 drivers/opp/opp.h                      |  13 +++++
 drivers/pci/controller/dwc/pcie-qcom.c |   3 +-
 include/linux/pm_opp.h                 |  13 +++++
 5 files changed, 163 insertions(+), 10 deletions(-)
---
base-commit: c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9
change-id: 20250717-opp_pcie-793160b2b113

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