linux-kernel - Re: [PATCH V2] arm64: dts: qcom: sc7180: Add bandwidth votes for eMMC and SDcard

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Date:   Fri, 24 Jul 2020 10:10:18 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Shaik Sajida Bhanu <sbhanu@...eaurora.org>
Cc:     adrian.hunter@...el.com, ulf.hansson@...aro.org,
        robh+dt@...nel.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, rnayak@...eaurora.org,
        Pradeep P V K <ppvk@...eaurora.org>
Subject: Re: [PATCH V2] arm64: dts: qcom: sc7180: Add bandwidth votes for
 eMMC and SDcard

Hi Shaik,

On Tue, Jul 21, 2020 at 04:16:21PM +0530, Shaik Sajida Bhanu wrote:
> From: Pradeep P V K <ppvk@...eaurora.org>
> 
> Add the bandwidth domain supporting performance state and
> the corresponding OPP tables for the sdhc device on sc7180.
> 
> Signed-off-by: Pradeep P V K <ppvk@...eaurora.org>
> Signed-off-by: Shaik Sajida Bhanu <sbhanu@...eaurora.org>
> ---
> 
> Changes since V1:
> 	- Incorporated review comments by Bjorn Andersson.
> ---
>  arch/arm64/boot/dts/qcom/sc7180.dtsi | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> index 68f9894..d78a066 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> @@ -684,6 +684,9 @@
>  			clocks = <&gcc GCC_SDCC1_APPS_CLK>,
>  					<&gcc GCC_SDCC1_AHB_CLK>;
>  			clock-names = "core", "iface";
> +			interconnects = <&aggre1_noc MASTER_EMMC &mc_virt SLAVE_EBI1>,
> +				<&gem_noc MASTER_APPSS_PROC &config_noc SLAVE_EMMC_CFG>;
> +			interconnect-names = "sdhc-ddr","cpu-sdhc";
>  			power-domains = <&rpmhpd SC7180_CX>;
>  			operating-points-v2 = <&sdhc1_opp_table>;
>  
> @@ -704,11 +707,15 @@
>  				opp-100000000 {
>  					opp-hz = /bits/ 64 <100000000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
> +					opp-peak-kBps = <100000 100000>;
> +					opp-avg-kBps = <100000 50000>;
>  				};
>  
>  				opp-384000000 {
>  					opp-hz = /bits/ 64 <384000000>;
>  					required-opps = <&rpmhpd_opp_svs_l1>;
> +					opp-peak-kBps = <600000 900000>;
> +					opp-avg-kBps = <261438 300000>;
>  				};
>  			};
>  		};
> @@ -2476,6 +2483,10 @@
>  			clocks = <&gcc GCC_SDCC2_APPS_CLK>,
>  					<&gcc GCC_SDCC2_AHB_CLK>;
>  			clock-names = "core", "iface";
> +
> +			interconnects = <&aggre1_noc MASTER_SDCC_2 &mc_virt SLAVE_EBI1>,
> +				<&gem_noc MASTER_APPSS_PROC &config_noc	SLAVE_SDCC_2>;
> +			interconnect-names = "sdhc-ddr","cpu-sdhc";
>  			power-domains = <&rpmhpd SC7180_CX>;
>  			operating-points-v2 = <&sdhc2_opp_table>;
>  
> @@ -2489,11 +2500,15 @@
>  				opp-100000000 {
>  					opp-hz = /bits/ 64 <100000000>;
>  					required-opps = <&rpmhpd_opp_low_svs>;
> +					opp-peak-kBps = <160000 100000>;
> +					opp-avg-kBps = <80000 50000>;
>  				};
>  
>  				opp-202000000 {
>  					opp-hz = /bits/ 64 <202000000>;
>  					required-opps = <&rpmhpd_opp_svs_l1>;
> +					opp-peak-kBps = <200000	120000>;
> +					opp-avg-kBps = <100000 60000>;
>  				};
>  			};
>  		};

Does the sdhci-msm driver actually have BW scaling support at this point?

There is commit 4ece9795be56 ("mmc: sdhci-msm: Add interconnect
bandwidth scaling support"), whose commit message says "make sure
interconnect driver is ready before handling interconnect scaling.".

I haven't seen any patch adding the scaling support (supposedly by
adding dev_pm_opp_set_bw() calls?). Did I miss it? If not it seems
it would make sense to post it in a series together with this patch,
as far as I can tell this patch alone does nothing in practical terms.

grep sdhc /sys/kernel/debug/interconnect/interconnect_summary
  8804000.sdhci                          0            0            0
  7c4000.sdhci                           0            0            0
  7c4000.sdhci                           0            0            0
  8804000.sdhci                          0            0            0
  ...