linux-kernel - Re: [PATCH 2/4] arm64: dts: qcom: msm8996: Pass VDDMX to gpu in power-domains

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Message-ID: <CAA8EJprbBHTco078ix5=4OrxFm9cLVi0AbhCRVfr=-O2S0V2CQ@mail.gmail.com>
Date:   Thu, 30 Mar 2023 00:29:29 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Vinod Koul <vkoul@...nel.org>, Rob Clark <robdclark@...il.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Andy Gross <andy.gross@...aro.org>
Subject: Re: [PATCH 2/4] arm64: dts: qcom: msm8996: Pass VDDMX to gpu in power-domains

On Wed, 29 Mar 2023 at 22:17, Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
> Since power-domains is used for perf_level pm_genpd scaling, it's only
> fitting that we pass a power domain that's actually supposed to be
> scaled (and not only turned on/off) to the GPU. While we don't quite
> support CPR3 yet, the next best thing we can do is pass VDDMX, so that
> we're at least guaranteed a reasonable vote on the memory side of
> things. Do so and leave a note mentioning CPR3 PD should be used here
> instead when support is added.
>
> Fixes: 69cc3114ab0f ("arm64: dts: Add Adreno GPU definitions")
> Fixes: 3f65d51e9e22 ("arm64: dts: qcom: msm8996: Make GPU node control GPU_GX GDSC")
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>  arch/arm64/boot/dts/qcom/msm8996.dtsi | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8996.dtsi b/arch/arm64/boot/dts/qcom/msm8996.dtsi
> index 4661a556772e..4dd37f72e018 100644
> --- a/arch/arm64/boot/dts/qcom/msm8996.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8996.dtsi
> @@ -1228,7 +1228,8 @@ gpu: gpu@...000 {
>                         interconnects = <&bimc MASTER_GRAPHICS_3D &bimc SLAVE_EBI_CH0>;
>                         interconnect-names = "gfx-mem";
>
> -                       power-domains = <&mmcc GPU_GX_GDSC>;
> +                       /* TODO: also scale VDDGFX with CPR3 */
> +                       power-domains = <&rpmpd MSM8996_VDDMX>;
>                         iommus = <&adreno_smmu 0>;
>
>                         nvmem-cells = <&speedbin_efuse>;
> @@ -2254,7 +2255,13 @@ adreno_smmu: iommu@...000 {
>                                  <&mmcc GPU_AHB_CLK>;
>                         clock-names = "bus", "iface";
>
> -                       power-domains = <&mmcc GPU_GDSC>;
> +                       /*
> +                        * We need both GPU_GDSC and GPU_GX_GDSC to be on, but the
> +                        * power-domains entry under gpu is occupied by the scaled
> +                        * voltage domain. Since GPU_GDSC is a parent of GX_GDSC,
> +                        * we can simply pass GX here to turn them both on!
> +                        */

Ugh. You can pass GX and VDDMX to the gpu. Let me send the patch
supporting that.

> +                       power-domains = <&mmcc GPU_GX_GDSC>;
>                 };
>
>                 venus: video-codec@...000 {
>
> --
> 2.40.0
>


-- 
With best wishes
Dmitry