linux-kernel - Re: [PATCH 0/8] Support dynamic EMC frequency scaling on Tegra186/Tegra194

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Message-ID: <cfffcabd-c33b-46f9-9b16-b6063ceee4c1@nvidia.com>
Date: Thu, 4 Sep 2025 17:17:40 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: webgeek1234@...il.com, Krzysztof Kozlowski <krzk@...nel.org>,
 Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 Thierry Reding <thierry.reding@...il.com>,
 Jonathan Hunter <jonathanh@...dia.com>, "Rafael J. Wysocki"
 <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, bbasu@...dia.com, sumitg@...dia.com
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 0/8] Support dynamic EMC frequency scaling on
 Tegra186/Tegra194

On 01/09/25 09:03, Aaron Kling via B4 Relay wrote:
> External email: Use caution opening links or attachments
>
>
> This series borrows the concept used on Tegra234 to scale EMC based on
> CPU frequency and applies it to Tegra186 and Tegra194. Except that the
> bpmp on those archs does not support bandwidth manager, so the scaling
> iteself is handled similar to how Tegra124 currently works.
>
> Signed-off-by: Aaron Kling <webgeek1234@...il.com>
> ---

Tegra186/194 had multiple drivers for BWMGR, ISOMGR and LA+PTSA configs
on the CPU side. I am not sure how effective this patch series will be 
in absence
of those components. In Tegra234, those were moved to BPMP-FW. So, Kernel
forwards the BW request to BPMP (R5) who takes care of setting the final 
freq.

Thank you,
Sumit Gupta

> Aaron Kling (8):
>        dt-bindings: tegra: Add ICC IDs for dummy memory clients for Tegra186
>        dt-bindings: tegra: Add ICC IDs for dummy memory clients for Tegra194
>        cpufreq: tegra186: add OPP support and set bandwidth
>        memory: tegra186-emc: Support non-bpmp icc scaling
>        memory: tegra186: Support icc scaling
>        memory: tegra194: Support icc scaling
>        arm64: tegra: Add CPU OPP tables for Tegra186
>        arm64: tegra: Add CPU OPP tables for Tegra194
>
>   arch/arm64/boot/dts/nvidia/tegra186.dtsi | 317 +++++++++++++++
>   arch/arm64/boot/dts/nvidia/tegra194.dtsi | 636 +++++++++++++++++++++++++++++++
>   drivers/cpufreq/tegra186-cpufreq.c       | 152 +++++++-
>   drivers/memory/tegra/tegra186-emc.c      | 132 ++++++-
>   drivers/memory/tegra/tegra186.c          |  48 +++
>   drivers/memory/tegra/tegra194.c          |  59 ++-
>   include/dt-bindings/memory/tegra186-mc.h |   4 +
>   include/dt-bindings/memory/tegra194-mc.h |   6 +
>   8 files changed, 1344 insertions(+), 10 deletions(-)
> ---
> base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
> change-id: 20250823-tegra186-icc-7299110cd774
> prerequisite-change-id: 20250826-tegra186-cpufreq-fixes-7fbff81c68a2:v3
> prerequisite-patch-id: 74a2633b412b641f9808306cff9b0a697851d6c8
> prerequisite-patch-id: 9c52827317f7abfb93885febb1894b40967bd64c
>
> Best regards,
> --
> Aaron Kling <webgeek1234@...il.com>
>
>
>