linux-kernel - Re: [PATCH v8 00/13] coresight: Update timestamp attribute to be an interval instead of bool

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Message-ID: <176763112483.1193329.14214589661973805304.b4-ty@arm.com>
Date: Mon,  5 Jan 2026 16:39:33 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Mike Leach <mike.leach@...aro.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>,
	Leo Yan <leo.yan@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	James Clark <james.clark@...aro.org>
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	Jie Gan <jie.gan@....qualcomm.com>
Subject: Re: [PATCH v8 00/13] coresight: Update timestamp attribute to be an interval instead of bool


On Fri, 28 Nov 2025 11:55:12 +0000, James Clark wrote:
> Do some cleanups then expand the timestamp format attribute from 1 bit
> to 4 bits for ETMv4 in Perf mode. The current interval is too high for
> most use cases, and particularly on the FVP the number of timestamps
> generated is excessive. This change not only still allows disabling or
> enabling timestamps, but also allows the interval to be configured.
> 
> The old bit is kept deprecated and undocumented for now. There are known
> broken versions of Perf that don't read the format attribute positions
> from sysfs and instead hard code the timestamp bit. We can leave the old
> bit in the driver until we need the bit for another feature or enough
> time has passed that these old Perfs are unlikely to be used.
> 
> [...]

Applied, thanks!

[01/13] coresight: Change syncfreq to be a u8
        (no commit info)
[02/13] coresight: Repack struct etmv4_drvdata
        (no commit info)
[03/13] coresight: Refactor etm4_config_timestamp_event()
        (no commit info)
[04/13] coresight: Hide unused ETMv3 format attributes
        (no commit info)
[05/13] coresight: Define format attributes with GEN_PMU_FORMAT_ATTR()
        (no commit info)
[06/13] coresight: Interpret ETMv3 config with ATTR_CFG_GET_FLD()
        (no commit info)
[07/13] coresight: Don't reject unrecognized ETMv3 format attributes
        (no commit info)
[08/13] coresight: Interpret perf config with ATTR_CFG_GET_FLD()
        (no commit info)
[09/13] coresight: Interpret ETMv4 config with ATTR_CFG_GET_FLD()
        (no commit info)
[10/13] coresight: Remove misleading definitions
        (no commit info)
[11/13] coresight: Prepare to allow setting the timestamp interval
        (no commit info)
[12/13] coresight: Extend width of timestamp format attribute
        (no commit info)
[13/13] coresight: docs: Document etm4x timestamp interval option
        (no commit info)

Best regards,
-- 
Suzuki K Poulose <suzuki.poulose@....com>