linux-kernel - Re: [PATCH v4 3/7] arm64: dts: qcom: sm8450: Add opp-level to indicate PCIe data rates

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Message-ID: <6nwss6gl3d47zer4pai23xcu4weok7m3ptyuptvu5oli7u7ads@zzhbw67hnhz5>
Date: Tue, 26 Aug 2025 11:27:11 +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 v4 3/7] arm64: dts: qcom: sm8450: Add opp-level to
 indicate PCIe data rates

On Wed, Aug 20, 2025 at 01:58:49PM GMT, Krishna Chaitanya Chundru wrote:
> Add opp-level to indicate PCIe data rates and also define OPP enteries
> for each link width and data rate. Append the opp level to name of the
> opp node to indicate both frequency and level.
> 

First define the problem statement of why this change is needed. You've
mentioned it in the cover letter, but that won't be preserved in git history.
Then you need to justify the change and make it clear that *this* platform
doesn't suffer the issue but you are doing it for the unification.

This needs to be done for all DTS patches.

- Mani

> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/sm8450.dtsi | 41 +++++++++++++++++++++++++++++-------
>  1 file changed, 33 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sm8450.dtsi b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> index 33574ad706b915136546c7f92c7cd0b8a0d62b7e..d7f8706ca4949e253a4102474c92b393a345262f 100644
> --- a/arch/arm64/boot/dts/qcom/sm8450.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> @@ -2052,6 +2052,7 @@ opp-2500000 {
>  					opp-hz = /bits/ 64 <2500000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
>  					opp-peak-kBps = <250000 1>;
> +					opp-level = <1>;
>  				};
>  
>  				/* GEN 2 x1 */
> @@ -2059,6 +2060,7 @@ opp-5000000 {
>  					opp-hz = /bits/ 64 <5000000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
>  					opp-peak-kBps = <500000 1>;
> +					opp-level = <2>;
>  				};
>  
>  				/* GEN 3 x1 */
> @@ -2066,6 +2068,7 @@ opp-8000000 {
>  					opp-hz = /bits/ 64 <8000000>;
>  					required-opps = <&rpmhpd_opp_nom>;
>  					opp-peak-kBps = <984500 1>;
> +					opp-level = <3>;
>  				};
>  			};
>  
> @@ -2210,45 +2213,67 @@ pcie1_opp_table: opp-table {
>  				compatible = "operating-points-v2";
>  
>  				/* GEN 1 x1 */
> -				opp-2500000 {
> +				opp-2500000-1 {
>  					opp-hz = /bits/ 64 <2500000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
>  					opp-peak-kBps = <250000 1>;
> +					opp-level = <1>;
>  				};
>  
> -				/* GEN 1 x2 and GEN 2 x1 */
> -				opp-5000000 {
> +				/* GEN 1 x2 */
> +				opp-5000000-1 {
> +					opp-hz = /bits/ 64 <5000000>;
> +					required-opps = <&rpmhpd_opp_low_svs>;
> +					opp-peak-kBps = <500000 1>;
> +					opp-level = <1>;
> +				};
> +
> +				/* GEN 2 x1 */
> +				opp-5000000-2 {
>  					opp-hz = /bits/ 64 <5000000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
>  					opp-peak-kBps = <500000 1>;
> +					opp-level = <2>;
>  				};
>  
>  				/* GEN 2 x2 */
> -				opp-10000000 {
> +				opp-10000000-2 {
>  					opp-hz = /bits/ 64 <10000000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
>  					opp-peak-kBps = <1000000 1>;
> +					opp-level = <2>;
>  				};
>  
>  				/* GEN 3 x1 */
> -				opp-8000000 {
> +				opp-8000000-3 {
>  					opp-hz = /bits/ 64 <8000000>;
>  					required-opps = <&rpmhpd_opp_nom>;
>  					opp-peak-kBps = <984500 1>;
> +					opp-level = <3>;
> +				};
> +
> +				/* GEN 3 x2 */
> +				opp-16000000-3 {
> +					opp-hz = /bits/ 64 <16000000>;
> +					required-opps = <&rpmhpd_opp_nom>;
> +					opp-peak-kBps = <1969000 1>;
> +					opp-level = <3>;
>  				};
>  
> -				/* GEN 3 x2 and GEN 4 x1 */
> -				opp-16000000 {
> +				/* GEN 4 x1 */
> +				opp-16000000-4 {
>  					opp-hz = /bits/ 64 <16000000>;
>  					required-opps = <&rpmhpd_opp_nom>;
>  					opp-peak-kBps = <1969000 1>;
> +					opp-level = <4>;
>  				};
>  
>  				/* GEN 4 x2 */
> -				opp-32000000 {
> +				opp-32000000-4 {
>  					opp-hz = /bits/ 64 <32000000>;
>  					required-opps = <&rpmhpd_opp_nom>;
>  					opp-peak-kBps = <3938000 1>;
> +					opp-level = <4>;
>  				};
>  			};
>  
> 
> -- 
> 2.34.1
> 

-- 
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