linux-kernel - Re: [PATCH v5 0/5] OPP: Add support to find OPP for a set of keys

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Message-ID: <eedvr7oojrp74opshopbjehiuqixa6q3a5tuxni6gni6bacexk@ktrsutu32tqs>
Date: Sun, 26 Oct 2025 21:57:48 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, 
	Stephen Boyd <sboyd@...nel.org>, "Rafael J. Wysocki" <rafael@...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>, 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
Subject: Re: [PATCH v5 0/5] OPP: Add support to find OPP for a set of keys

On Mon, Oct 13, 2025 at 04:23:27PM +0530, Krishna Chaitanya Chundru wrote:
> 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_key_exact() that allows OPP lookup for set of keys like
> frequency, level & bandwidth.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
> Changes in v5:
> - Add support for legacy devicetree's (Neil).
> - Update commit text and comments to use data rates instead of GEN (Mani).
> - Link to v4: https://lore.kernel.org/r/20250820-opp_pcie-v4-0-273b8944eed0@oss.qualcomm.com
> 
> Changes in v4:
> - Included dtsi changes for all platforms.
> - Made the changes as requested by Viresh like adding comments, some
>   coding styles etc.
> - Link to v3: https://lore.kernel.org/r/20250819-opp_pcie-v3-0-f8bd7e05ce41@oss.qualcomm.com
> 
> Changes in v3:
> - Always check for frequency match unless user doesn't pass it (Viresh).
> - Make dev_pm_opp_key public and let user pass the key (Viresh).
> - Include bandwidth as part of dev_pm_opp_key (Viresh).
> - Link to v2: https://lore.kernel.org/r/20250818-opp_pcie-v2-0-071524d98967@oss.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 (5):
>       arm64: dts: qcom: sm8450: Add opp-level to indicate PCIe data rates
>       arm64: dts: qcom: sm8550: Add opp-level to indicate PCIe data rates
>       arm64: dts: qcom: sm8650: Add opp-level to indicate PCIe data rates
>       arm64: dts: qcom: x1e80100: Add opp-level to indicate PCIe data rates
>       PCI: qcom: Use frequency and level based OPP lookup
> 
>  arch/arm64/boot/dts/qcom/sm8450.dtsi   | 55 +++++++++++++------
>  arch/arm64/boot/dts/qcom/sm8550.dtsi   | 79 +++++++++++++++++++--------
>  arch/arm64/boot/dts/qcom/sm8650.dtsi   | 79 +++++++++++++++++++--------
>  arch/arm64/boot/dts/qcom/x1e80100.dtsi | 98 +++++++++++++++++++++++++++-------

Acked-by: Manivannan Sadhasivam <mani@...nel.org>

- Mani

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