linux-kernel - Re: [PATCH v4 0/7] Arm CoreSight: Support AUX pause and resume

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Message-ID: <2ef27237-e5b4-4c9c-9810-9d1800d96596@linaro.org>
Date: Thu, 1 May 2025 11:11:35 +0100
From: James Clark <james.clark@...aro.org>
To: Leo Yan <leo.yan@....com>, Suzuki K Poulose <suzuki.poulose@....com>
Cc: Mike Leach <mike.leach@...aro.org>, Jonathan Corbet <corbet@....net>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/7] Arm CoreSight: Support AUX pause and resume



On 01/04/2025 7:07 pm, Leo Yan wrote:
> This series is to enable AUX pause and resume on Arm CoreSight.
> 
> The first patch extracts the trace unit controlling operations to two
> functions.  These two functions will be used by AUX pause and resume.
> 
> Patches 02 and 03 change the ETMv4 driver to prepare callback functions
> for AUX pause and resume.
> 
> Patch 04 changes the ETM perf layer to support AUX pause and resume in a
> perf session.  The patch 05 re-enables sinks after buffer update, based
> on it, the patch 06 updates buffer on AUX pause occasion, which can
> mitigate the trace data lose issue.
> 
> Patch 07 documents the AUX pause usages with Arm CoreSight.
> 
> This patch set has been verified on the Hikey960 board.
> 
> It is suggested to disable CPUIdle (add `nohlt` option in Linux command
> line) when verifying this series.  ETM and funnel drivers are found
> issues during CPU suspend and resume which will be addressed separately.
> 
> Changes from v3:
> - Re-enabled sink in buffer update callbacks (Suzuki).
> 
> Changes from v2:
> - Rebased on CoreSight next branch.
> - Dropped the uAPI 'update_buf_on_pause' and updated document
>    respectively (Suzuki).
> - Renamed ETM callbacks to .pause_perf() and .resume_perf() (Suzuki).
> - Minor improvement for error handling in the AUX resume flow.
> 
> Changes from v1:
> - Added validation function pointers in pause and resume APIs (Mike).
> 
> 
> Leo Yan (7):
>    coresight: etm4x: Extract the trace unit controlling
>    coresight: Introduce pause and resume APIs for source
>    coresight: etm4x: Hook pause and resume callbacks
>    coresight: perf: Support AUX trace pause and resume
>    coresight: tmc: Re-enable sink after buffer update
>    coresight: perf: Update buffer on AUX pause
>    Documentation: coresight: Document AUX pause and resume
> 
>   Documentation/trace/coresight/coresight-perf.rst   |  31 +++++++++
>   drivers/hwtracing/coresight/coresight-core.c       |  22 +++++++
>   drivers/hwtracing/coresight/coresight-etm-perf.c   |  84 +++++++++++++++++++++++-
>   drivers/hwtracing/coresight/coresight-etm4x-core.c | 143 +++++++++++++++++++++++++++++------------
>   drivers/hwtracing/coresight/coresight-etm4x.h      |   2 +
>   drivers/hwtracing/coresight/coresight-priv.h       |   2 +
>   drivers/hwtracing/coresight/coresight-tmc-etf.c    |   9 +++
>   drivers/hwtracing/coresight/coresight-tmc-etr.c    |  10 +++
>   include/linux/coresight.h                          |   4 ++
>   9 files changed, 265 insertions(+), 42 deletions(-)
> 

Reviewed-by: James Clark <james.clark@...aro.org>