linux-kernel - [PATCH v3 0/6] Refactoring finding CPU phandles in DT

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Message-ID: <20250718094848.587-1-alireza.sanaee@huawei.com>
Date: Fri, 18 Jul 2025 10:48:42 +0100
From: Alireza Sanaee <alireza.sanaee@...wei.com>
To: <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <jonathan.cameron@...wei.com>, <coresight@...ts.linaro.org>,
	<dianders@...omium.org>, <james.clark@...aro.org>, <krzk@...nel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-perf-users@...r.kernel.org>,
	<linuxarm@...wei.com>, <mark.rutland@....com>, <mike.leach@...aro.org>,
	<robh@...nel.org>, <ruanjinjie@...wei.com>, <saravanak@...gle.com>,
	<shameerali.kolothum.thodi@...wei.com>, <suzuki.poulose@....com>
Subject: [PATCH v3 0/6] Refactoring finding CPU phandles in DT

This series refactor the way CPU IDs are retrieved from the device
tree.

Usually, there is a for loop that goes over every single CPU that can be
avoided. This also reduces the amount of NULL pointer checks in drivers.
I have abstracted away that loop and introduced a new function
(of_cpu_node_to_id) for this.

This patchset is a subset of [1], where I removed content and patches
relevant to hyper-threaded cores for DT. Based on the discussion, the
code refactor is still useful, hence this patchset.

[1]
https://lore.kernel.org/all/20250512080715.82-1-alireza.sanaee@huawei.co

Changes since v2:
    - Addressed Jonathan Cameron's comments.
    - Added reviewed-by tags.
    - Added a new commit where I suggest simplfing the code in
      arch_topology.c to remove the use of cpu_node on failure path.
    - Improve documentation.
    - Caught a bug in patch 1.
    - Commit message fixed for patch 2.

Changes since v1:
    - Rebased on top of the latest mainline.
    - Addressed Krzysztof Kozlowski's comments -- Hopefully :-)
    - Addressed Jonathan Cameron's comments.

Alireza Sanaee (6):
  of: add infra for finding CPU id from phandle
  arch_topology: drop the use of cpu_node in the pr_info
  arch_topology: update CPU map to use of_cpu_phandle_to_id
  coresight: cti: Use of_cpu_phandle_to_id for grabbing CPU id
  coresight: Use of_cpu_phandle_to_id for grabbing CPU ID
  perf/arm-dsu: refactor cpu id retrieval via new API
    of_cpu_phandle_to_id

 drivers/base/arch_topology.c                  | 22 ++++-----
 .../coresight/coresight-cti-platform.c        | 13 +----
 .../hwtracing/coresight/coresight-platform.c  | 15 +-----
 drivers/of/cpu.c                              | 49 +++++++++++++++++++
 drivers/perf/arm_dsu_pmu.c                    |  7 +--
 include/linux/of.h                            |  9 ++++
 6 files changed, 72 insertions(+), 43 deletions(-)

-- 
2.43.0