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

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Message-ID: <53e92af3-67cb-425a-a9c0-5746ce349247@arm.com>
Date: Mon, 5 Jan 2026 16:45:53 +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: 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 05/01/2026 16:39, Suzuki K Poulose wrote:
> 
> 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)

Indeed they were applied, ;-)

https://git.kernel.org/coresight/c/19214ad0a4e3
https://git.kernel.org/coresight/c/6c75940eb76d
https://git.kernel.org/coresight/c/f4d2f5fec06a
https://git.kernel.org/coresight/c/3285c471d0c0
https://git.kernel.org/coresight/c/afed86e6e141
https://git.kernel.org/coresight/c/b945d3677754
https://git.kernel.org/coresight/c/d633fd22e810
https://git.kernel.org/coresight/c/a1d19cd2b1a6
https://git.kernel.org/coresight/c/458db6257149
https://git.kernel.org/coresight/c/20bc2ea23774
https://git.kernel.org/coresight/c/b02450de6ba6
https://git.kernel.org/coresight/c/38f4c4273499
https://git.kernel.org/coresight/c/10d4dbdc8fbc


Suzuki
> 
> Best regards,