linux-kernel - [PATCH v5 5/5] PCI: qcom: Use frequency and level based OPP lookup

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Message-Id: <20251013-opp_pcie-v5-5-eb64db2b4bd3@oss.qualcomm.com>
Date: Mon, 13 Oct 2025 16:23:32 +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 v5 5/5] PCI: qcom: Use frequency and level based OPP lookup

PCIe link configurations such as 8GT/s x2 and 16GT/s x1 may operate at
the same frequency but differ in other characteristics like RPMh votes.
The existing OPP selection based solely on frequency cannot distinguish
between such cases.

In such cases, frequency alone is insufficient to identify the correct OPP.
Use the newly introduced dev_pm_opp_find_key_exact() API to match both
frequency and level when selecting an OPP, here level indicates PCIe
data rate.

To support older device tree's where opp-level is not defined, check if
opp-level is present or not using dev_pm_opp_find_level_exact(). if
not present fallback to frequency only match.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 805edbbfe7eba496bc99ca82051dee43d240f359..03b3a1d3a40359a0c70704873b72539ffa43e722 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1565,6 +1565,7 @@ static void qcom_pcie_icc_opp_update(struct qcom_pcie *pcie)
 {
 	u32 offset, status, width, speed;
 	struct dw_pcie *pci = pcie->pci;
+	struct dev_pm_opp_key key;
 	unsigned long freq_kbps;
 	struct dev_pm_opp *opp;
 	int ret, freq_mbps;
@@ -1592,8 +1593,20 @@ static void qcom_pcie_icc_opp_update(struct qcom_pcie *pcie)
 			return;
 
 		freq_kbps = freq_mbps * KILO;
-		opp = dev_pm_opp_find_freq_exact(pci->dev, freq_kbps * width,
-						 true);
+		opp = dev_pm_opp_find_level_exact(pci->dev, speed);
+		if (IS_ERR(opp)) {
+			 /* opp-level is not defined use only frequency */
+			opp = dev_pm_opp_find_freq_exact(pci->dev, freq_kbps * width,
+							 true);
+		} else {
+			/* put opp-level OPP */
+			dev_pm_opp_put(opp);
+
+			key.freq = freq_kbps * width;
+			key.level = speed;
+			key.bw = 0;
+			opp = dev_pm_opp_find_key_exact(pci->dev, &key, true);
+		}
 		if (!IS_ERR(opp)) {
 			ret = dev_pm_opp_set_opp(pci->dev, opp);
 			if (ret)

-- 
2.34.1