Re: [PATCH v2 00/12] coresight: Add CPU cluster funnel/replicator/tmc support
From: Suzuki K Poulose
Date: Thu Dec 18 2025 - 12:04:14 EST
On 18/12/2025 16:18, yuanfang zhang wrote:
On 12/18/2025 5:32 PM, Suzuki K Poulose wrote:
Cc: SudeepHi Suzuki
On 18/12/2025 08:09, Yuanfang Zhang wrote:
This patch series adds support for CoreSight components local to CPU clusters,
including funnel, replicator, and TMC, which reside within CPU cluster power
domains. These components require special handling due to power domain
constraints.
Unlike system-level CoreSight devices, these components share the CPU cluster's
power domain. When the cluster enters low-power mode (LPM), their registers
become inaccessible. Notably, `pm_runtime_get` alone cannot bring the cluster
out of LPM, making standard register access unreliable.
Why ? AFAIU, we have ways to tie the power-domain to that of the cluster
and that can auto-magically keep the cluster power ON as long as you
want to use them.
Suzuki
Runtime PM for CPU devices works little different, it is mostly used to manage hierarchical
CPU topology (PSCI OSI mode) to talk with genpd framework to manage the last CPU handling in
cluster.
It doesn’t really send IPI to wakeup CPU device (It don’t have .power_on/.power_off) callback
implemented which gets invoked from .runtime_resume callback. This behavior is aligned with
the upstream Kernel.
Why does it need to wake up the CPU ? The firmware can power up the
cluster right? Anyways, to me this all looks like working around a
firmware issue. I will let you sort this out with Sudeep's response
, as I am not an expert on the cluster powermanagement and standards.
Suzuki
Yuanfang
To address this, the series introduces:
- Identifying cluster-bound devices via a new `qcom,cpu-bound-components`
device tree property.
- Implementing deferred probing: if associated CPUs are offline during
probe, initialization is deferred until a CPU hotplug notifier detects
the CPU coming online.
- Utilizing `smp_call_function_single()` to ensure register accesses
(initialization, enablement, sysfs reads) are always executed on a
powered CPU within the target cluster.
- Extending the CoreSight link `enable` callback to pass the `cs_mode`.
This allows drivers to distinguish between SysFS and Perf modes and
apply mode-specific logic.
Jie Gan (1):
arm64: dts: qcom: hamoa: add Coresight nodes for APSS debug block
Yuanfang Zhang (11):
dt-bindings: arm: coresight: Add 'qcom,cpu-bound-components' property
coresight: Pass trace mode to link enable callback
coresight-funnel: Support CPU cluster funnel initialization
coresight-funnel: Defer probe when associated CPUs are offline
coresight-replicator: Support CPU cluster replicator initialization
coresight-replicator: Defer probe when associated CPUs are offline
coresight-replicator: Update management interface for CPU-bound devices
coresight-tmc: Support probe and initialization for CPU cluster TMCs
coresight-tmc-etf: Refactor enable function for CPU cluster ETF support
coresight-tmc: Update management interface for CPU-bound TMCs
coresight-tmc: Defer probe when associated CPUs are offline
Verification:
This series has been verified on sm8750.
Test steps for delay probe:
1. limit the system to enable at most 6 CPU cores during boot.
2. echo 1 >/sys/bus/cpu/devices/cpu6/online.
3. check whether ETM6 and ETM7 have been probed.
Test steps for sysfs mode:
echo 1 >/sys/bus/coresight/devices/tmc_etf0/enable_sink
echo 1 >/sys/bus/coresight/devices/etm0/enable_source
echo 1 >/sys/bus/coresight/devices/etm6/enable_source
echo 0 >/sys/bus/coresight/devices/etm0/enable_source
echo 0 >/sys/bus/coresight/devicse/etm6/enable_source
echo 0 >/sys/bus/coresight/devices/tmc_etf0/enable_sink
echo 1 >/sys/bus/coresight/devices/tmc_etf1/enable_sink
echo 1 >/sys/bus/coresight/devcies/etm0/enable_source
cat /dev/tmc_etf1 >/tmp/etf1.bin
echo 0 >/sys/bus/coresight/devices/etm0/enable_source
echo 0 >/sys/bus/coresight/devices/tmc_etf1/enable_sink
echo 1 >/sys/bus/coresight/devices/tmc_etf2/enable_sink
echo 1 >/sys/bus/coresight/devices/etm6/enable_source
cat /dev/tmc_etf2 >/tmp/etf2.bin
echo 0 >/sys/bus/coresight/devices/etm6/enable_source
echo 0 >/sys/bus/coresight/devices/tmc_etf2/enable_sink
Test steps for sysfs node:
cat /sys/bus/coresight/devices/tmc_etf*/mgmt/*
cat /sys/bus/coresight/devices/funnel*/funnel_ctrl
cat /sys/bus/coresight/devices/replicator*/mgmt/*
Test steps for perf mode:
perf record -a -e cs_etm//k -- sleep 5
Signed-off-by: Yuanfang Zhang <yuanfang.zhang@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- Use the qcom,cpu-bound-components device tree property to identify devices
bound to a cluster.
- Refactor commit message.
- Introduce a supported_cpus field in the drvdata structure to record the CPUs
that belong to the cluster where the local component resides.
- Link to v1: https://lore.kernel.org/r/20251027-cpu_cluster_component_pm-v1-0-31355ac588c2@xxxxxxxxxxxxxxxx
---
Jie Gan (1):
arm64: dts: qcom: hamoa: Add CoreSight nodes for APSS debug block
Yuanfang Zhang (11):
dt-bindings: arm: coresight: Add 'qcom,cpu-bound-components' property
coresight-funnel: Support CPU cluster funnel initialization
coresight-funnel: Defer probe when associated CPUs are offline
coresight-replicator: Support CPU cluster replicator initialization
coresight-replicator: Defer probe when associated CPUs are offline
coresight-replicator: Update management interface for CPU-bound devices
coresight-tmc: Support probe and initialization for CPU cluster TMCs
coresight-tmc-etf: Refactor enable function for CPU cluster ETF support
coresight-tmc: Update management interface for CPU-bound TMCs
coresight-tmc: Defer probe when associated CPUs are offline
coresight: Pass trace mode to link enable callback
.../bindings/arm/arm,coresight-dynamic-funnel.yaml | 5 +
.../arm/arm,coresight-dynamic-replicator.yaml | 5 +
.../devicetree/bindings/arm/arm,coresight-tmc.yaml | 5 +
arch/arm64/boot/dts/qcom/hamoa.dtsi | 926 +++++++++++++++++++++
arch/arm64/boot/dts/qcom/purwa.dtsi | 12 +
drivers/hwtracing/coresight/coresight-core.c | 7 +-
drivers/hwtracing/coresight/coresight-funnel.c | 258 +++++-
drivers/hwtracing/coresight/coresight-replicator.c | 341 +++++++-
drivers/hwtracing/coresight/coresight-tmc-core.c | 387 +++++++--
drivers/hwtracing/coresight/coresight-tmc-etf.c | 106 ++-
drivers/hwtracing/coresight/coresight-tmc.h | 10 +
drivers/hwtracing/coresight/coresight-tnoc.c | 3 +-
drivers/hwtracing/coresight/coresight-tpda.c | 3 +-
include/linux/coresight.h | 3 +-
14 files changed, 1902 insertions(+), 169 deletions(-)
---
base-commit: 008d3547aae5bc86fac3eda317489169c3fda112
change-id: 20251016-cpu_cluster_component_pm-ce518f510433
Best regards,