linux-kernel - [PATCH RFC 0/7] Support Tegra210 actmon for dynamic EMC scaling

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Message-Id: <20250828-t210-actmon-v1-0-aeb19ec1f244@gmail.com>
Date: Thu, 28 Aug 2025 23:01:26 -0500
From: Aaron Kling via B4 Relay <devnull+webgeek1234.gmail.com@...nel.org>
To: 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>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 MyungJoo Ham <myungjoo.ham@...sung.com>, 
 Kyungmin Park <kyungmin.park@...sung.com>, 
 Chanwoo Choi <cw00.choi@...sung.com>, Dmitry Osipenko <digetx@...il.com>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org, 
 Aaron Kling <webgeek1234@...il.com>
Subject: [PATCH RFC 0/7] Support Tegra210 actmon for dynamic EMC scaling

This series adds interconnect support to tegra210 MC and EMC, then
enables actmon. This enables dynamic emc scaling.

This series is marked RFC for two reasons:

1) Calculating rate from bandwidth usage results in double the expected
   rate. I thought this might be due to the ram being 64-bit, but the
   related CFG5 register reports 32-bit on both p2371-2180 and
   p3450-0000. I'm using the calculation used for Tegra124 and haven't
   seen seen anything obviously different between the ram handling on
   these archs to cause a different result. I have considered that the
   number of channels might affect the reporting, and factoring in that
   variable does result in the correct rate, but I don't want to assume
   that's correct without confirmation.

2) I am seeing intermittent instability when transitioning to rates of
   204 MHz or below on p2371-2180. I have noted that if the first
   transition to such a state works, then it continues to work for the
   rest of that boot cycle. But the kernel will often panic the first
   time it tries to downclock. I suspect this is a pre-existing issue
   only brought to light now because nothing would ever lower the clock
   rate previously.

Signed-off-by: Aaron Kling <webgeek1234@...il.com>
---
Aaron Kling (7):
      dt-bindings: memory: tegra210: Add memory client IDs
      dt-bindings: devfreq: tegra30-actmon: Add Tegra124 fallback for Tegra210
      soc: tegra: fuse: speedo-tegra210: Add soc speedo 2
      memory: tegra210: Support interconnect framework
      arm64: tegra: tegra210: Add actmon
      arm64: tegra: Add interconnect properties to Tegra210 device-tree
      arm64: tegra: Add OPP tables on Tegra210

 .../bindings/devfreq/nvidia,tegra30-actmon.yaml    |  13 +-
 .../boot/dts/nvidia/tegra210-peripherals-opp.dtsi  | 135 ++++++++++
 arch/arm64/boot/dts/nvidia/tegra210.dtsi           |  43 ++++
 drivers/memory/tegra/Kconfig                       |   1 +
 drivers/memory/tegra/tegra210-emc-core.c           | 276 ++++++++++++++++++++-
 drivers/memory/tegra/tegra210-emc.h                |  25 ++
 drivers/memory/tegra/tegra210.c                    |  81 ++++++
 drivers/soc/tegra/fuse/speedo-tegra210.c           |   1 +
 include/dt-bindings/memory/tegra210-mc.h           |  58 +++++
 9 files changed, 626 insertions(+), 7 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250822-t210-actmon-34904ce7ed0c
prerequisite-change-id: 20250812-tegra210-speedo-470691e8b8cc:v1
prerequisite-patch-id: 81859c81abbe79aed1cfbc95b4f5bcdc5637d6bd
prerequisite-patch-id: 98bda8855bcc57c59b2231b7808d4478301afe68
prerequisite-patch-id: 6e0b69d42ea542dc9f58b410abd5974644f75dc4
prerequisite-patch-id: 9e3b9b2fdb8d9c2264dfa7641d1aec84fb7aedd9
prerequisite-patch-id: ef4bcc4ddba7898b188fb3fc6e414a2662183f91

Best regards,
-- 
Aaron Kling <webgeek1234@...il.com>