linux-kernel - Re: [PATCH v5 00/10] coresight: Fix and improve clock usage

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4c1161d3-fc7d-4b3c-8197-7b632e85280f@linaro.org>
Date: Fri, 25 Jul 2025 09:45:27 +0100
From: James Clark <james.clark@...aro.org>
To: Leo Yan <leo.yan@....com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Suzuki K Poulose <suzuki.poulose@....com>,
 Mike Leach <mike.leach@...aro.org>,
 Anshuman Khandual <anshuman.khandual@....com>,
 Yeoreum Yun <yeoreum.yun@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v5 00/10] coresight: Fix and improve clock usage



On 24/07/2025 4:22 pm, Leo Yan wrote:
> This series fixes and improves clock usage in the Arm CoreSight drivers.
> 
> Based on the DT binding documents, the trace clock (atclk) is defined in
> some CoreSight modules, but support is absent. In most cases, the issue
> is hidden because the atclk clock is shared by multiple CoreSight
> modules and the clock is enabled anyway by other drivers. The first
> three patches address this issue.
> 
> The programming clock (pclk) management in CoreSight drivers does not
> use the devm_XXX() variant APIs, the drivers needs to manually disable
> and release clocks for errors and for normal module exit.  However, the
> drivers miss to disable clocks during module exit. The atclk may also
> not be disabled in CoreSight drivers during module exit. By using devm
> APIs, patches 04 and 05 fix clock disabling issues.
> 
> Another issue is pclk might be enabled twice in init phase - once by
> AMBA bus driver, and again by CoreSight drivers. This is fixed in
> patch 06.
> 
> Patches 07 to 10 refactor the clock related code. Patch 07 consolidates
> the clock initialization into a central place. Patch 08 polishes driver
> data allocation. Patch 09 makes the clock enabling sequence consistent.
> Patch 09 removes redundant condition checks and adds error handling in
> runtime PM.
> 
> This series has been verified on Arm64 Juno platform, for both DT and
> ACPI modes.
> 

Tested on N1SDP with ACPI:

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

> ---
> Changes in v5:
> - Skip clock management for ACPI devices (Suzuki).
> - Link to v4: https://lore.kernel.org/r/20250627-arm_cs_fix_clock_v4-v4-0-0ce0009c38f8@arm.com
> 
> Changes in v4:
> - Separated patch 07 into two patches, one is for clock consolidation
>    and another is for polishing driver data allocation (Anshuman).
> 
> Changes in v3:
> - Updated subjects for patches 04 and 05 (Anshuman).
> - Refined condition checking "if (dev_is_amba(dev))" in patch 07
>    (Anshuman).
> 
> ---
> Leo Yan (10):
>        coresight: tmc: Support atclk
>        coresight: catu: Support atclk
>        coresight: etm4x: Support atclk
>        coresight: Appropriately disable programming clocks
>        coresight: Appropriately disable trace bus clocks
>        coresight: Avoid enable programming clock duplicately
>        coresight: Consolidate clock enabling
>        coresight: Refactor driver data allocation
>        coresight: Make clock sequence consistent
>        coresight: Refactor runtime PM
> 
>   drivers/hwtracing/coresight/coresight-catu.c       | 53 ++++++++---------
>   drivers/hwtracing/coresight/coresight-catu.h       |  1 +
>   drivers/hwtracing/coresight/coresight-core.c       | 48 ++++++++++++++++
>   drivers/hwtracing/coresight/coresight-cpu-debug.c  | 41 +++++---------
>   drivers/hwtracing/coresight/coresight-ctcu-core.c  | 24 +++-----
>   drivers/hwtracing/coresight/coresight-etb10.c      | 18 ++----
>   drivers/hwtracing/coresight/coresight-etm3x-core.c | 17 ++----
>   drivers/hwtracing/coresight/coresight-etm4x-core.c | 32 ++++++-----
>   drivers/hwtracing/coresight/coresight-etm4x.h      |  4 +-
>   drivers/hwtracing/coresight/coresight-funnel.c     | 66 ++++++++--------------
>   drivers/hwtracing/coresight/coresight-replicator.c | 63 ++++++++-------------
>   drivers/hwtracing/coresight/coresight-stm.c        | 34 +++++------
>   drivers/hwtracing/coresight/coresight-tmc-core.c   | 48 ++++++++--------
>   drivers/hwtracing/coresight/coresight-tmc.h        |  2 +
>   drivers/hwtracing/coresight/coresight-tpiu.c       | 36 +++++-------
>   include/linux/coresight.h                          | 31 +---------
>   16 files changed, 228 insertions(+), 290 deletions(-)
> ---
> base-commit: a80198ba650f50d266d7fc4a6c5262df9970f9f2
> change-id: 20250627-arm_cs_fix_clock_v4-e24b1e1f8920
> 
> Best regards,