linux-kernel - Re: [PATCH v3 0/3] coresight: Add preferred trace id support

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Message-ID: <CAJ9a7VhG4qNLnT87J7OiXpygbtMRZ8uAvNhZhcRCBxovMEPDEg@mail.gmail.com>
Date: Thu, 18 Jul 2024 16:57:33 +0100
From: Mike Leach <mike.leach@...aro.org>
To: Mao Jinlong <quic_jinlmao@...cinc.com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>, James Clark <james.clark@....com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, coresight@...ts.linaro.org, 
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	Tingwei Zhang <quic_tingweiz@...cinc.com>, Yuanfang Zhang <quic_yuanfang@...cinc.com>, 
	Tao Zhang <quic_taozha@...cinc.com>, songchai <quic_songchai@...cinc.com>
Subject: Re: [PATCH v3 0/3] coresight: Add preferred trace id support

Hi,

I have detailed comments in the following patches but in summary we should:
1) consistently use the term "static trace id" for these devices where
the hardware sets a non-programmable trace ID
2) Simplify the patch set by introducing a new API function
int coresight_trace_id_get_system_static_id(int trace_id)
This would avoid having to change drivers which use the existing
function where no static ID is required.

Regards

Mike


On Wed, 26 Jun 2024 at 07:07, Mao Jinlong <quic_jinlmao@...cinc.com> wrote:
>
> Some HW has static trace id which cannot be changed via
> software programming. For this case, configure the trace id
> in device tree with "arm,trace-id = <xxx>", and
> call coresight_trace_id_get_system_id with the trace id value
> in device probe function. The id will be reserved for the HW
> all the time if the device is probed.
>
> Changes since V2:
> 1. Change "trace-id" to "arm,trace-id".
> 2. Add trace id flag for getting preferred id or ODD id.
>
> Changes since V1:
> 1. Add argument to coresight_trace_id_get_system_id for preferred id
> instead of adding new function coresight_trace_id_reserve_system_id.
> 2. Add constraint to trace-id in dt-binding file.
>
> Mao Jinlong (3):
>   dt-bindings: arm: Add arm,trace-id for coresight dummy source
>   coresight: Add support to get preferred id for system trace sources
>   coresight: dummy: Add reserve atid support for dummy source
>
>  .../sysfs-bus-coresight-devices-dummy-source  | 15 +++++
>  .../arm/arm,coresight-dummy-source.yaml       |  6 ++
>  drivers/hwtracing/coresight/coresight-dummy.c | 59 +++++++++++++++++--
>  .../hwtracing/coresight/coresight-platform.c  | 25 ++++++++
>  drivers/hwtracing/coresight/coresight-stm.c   |  2 +-
>  drivers/hwtracing/coresight/coresight-tpda.c  |  2 +-
>  .../hwtracing/coresight/coresight-trace-id.c  | 35 +++++++----
>  .../hwtracing/coresight/coresight-trace-id.h  | 11 +++-
>  include/linux/coresight.h                     |  1 +
>  9 files changed, 137 insertions(+), 19 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source
>
> --
> 2.41.0
>


--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK