NACK/Cmnt: [SRU][N][PATCH 0/3] Coresight fails to build on 6.8.0-102 due to missing function and arg definitions

Wed Feb 25 08:57:40 UTC 2026

On 21/02/2026 02:01, Noah Wager wrote:
> BugLink: https://bugs.launchpad.net/bugs/2142337
> 
> SRU Justification:
> 
> [Impact]
> 
> When CONFIG_CORESIGHT is enabled, noble 6.8.0-102 fails to build with the following errors:
> 
> ```
> drivers/hwtracing/coresight/coresight-catu.c: In function 'catu_init':
> drivers/hwtracing/coresight/coresight-catu.c:728:15: error: implicit declaration of function 'coresight_init_driver' [-Werror=implicit-function-declaration]
>    728 | ret = coresight_init_driver("catu", &catu_driver, &catu_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~
> drivers/hwtracing/coresight/coresight-catu.c: In function 'catu_exit':
> drivers/hwtracing/coresight/coresight-catu.c:736:9: error: implicit declaration of function 'coresight_remove_driver'; did you mean 'coresight_remove_links'? [-Werror=implicit-function-declaration]
>    736 | coresight_remove_driver(&catu_driver, &catu_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~~~
>        | coresight_remove_links
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function '__tmc_probe':
> drivers/hwtracing/coresight/coresight-tmc-core.c:500:65: error: 'id' undeclared (first use in this function); did you mean 'fd'?
>    500 | coresight_get_uci_data(id));
>        | ^~
>        | fd
> drivers/hwtracing/coresight/coresight-tmc-core.c:500:65: note: each undeclared identifier is reported only once for each function it appears in
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function 'tmc_init':
> drivers/hwtracing/coresight/coresight-tmc-core.c:728:16: error: implicit declaration of function 'coresight_init_driver' [-Werror=implicit-function-declaration]
>    728 | return coresight_init_driver("tmc", &tmc_driver, &tmc_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function 'tmc_exit':
> drivers/hwtracing/coresight/coresight-tmc-core.c:733:9: error: implicit declaration of function 'coresight_remove_driver'; did you mean 'coresight_remove_links'? [-Werror=implicit-function-declaration]
>    733 | coresight_remove_driver(&tmc_driver, &tmc_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~~~
>        | coresight_remove_links
> ```
> 
> These errors are a result of including the following patches in upstream stable updates, but missing some dependencies from the original patch sets:
> 
>    Error description: __tmc_probe:id not defined
>    Break commit: n/linux aaf260b9572e ("coresight: tmc: Move ACPI support from AMBA driver to platform driver")
>    Missing commit: 852e9a32058a ("coresight: stm: Extract device name from AMBA pid based table lookup")
>                    3ab210297c31 ("coresight: tmc: Extract device properties from AMBA pid based table lookup")
>    Patch series: "coresight: Move remaining AMBA ACPI devices into platform driver"
>                  (https://lists-ec2.linaro.org/archives/list/coresight@lists.linaro.org/thread/XGJAJMHSDE5P7YSX33CIW5DHKR6C343L/)
> 
>    Error description: coresight_{init,remove}_driver not defined
>    Break commit: n/linux aaf260b9572e ("coresight: tmc: Move ACPI support from AMBA driver to platform driver")
>    Missing commit: 075b7cd7ad7d ("coresight: Add helpers registering/removing both AMBA and platform drivers")
>    Patch series: "coresight: Move remaining AMBA ACPI devices into platform driver"
>                  (https://lists-ec2.linaro.org/archives/list/coresight@lists.linaro.org/thread/XGJAJMHSDE5P7YSX33CIW5DHKR6C343L/)
> 
> [Fix]
> 
> Cherry-pick upstream commits:
> 852e9a32058a ("coresight: stm: Extract device name from AMBA pid based table lookup")
> 3ab210297c31 ("coresight: tmc: Extract device properties from AMBA pid based table lookup")
> 075b7cd7ad7d ("coresight: Add helpers registering/removing both AMBA and platform drivers")
> from the series:
> "coresight: Move remaining AMBA ACPI devices into platform driver".
> 
> NOTE: The series also has "Move remaining AMBA ACPI devices into platform driver"
> commits for the remaining devices, but I elected not to port them. We have
> the respective commits for tmc and catu applied because they were
> dependencies of "{tmc,catu}: Support atclk", but since the commits for the
> other devices are not necessary for the patches to apply, and as of now there
> are no upstream stable candidates with "Fixes" for the other devices, I don't
> think it's worth the increased change size. Fortunately, if they are needed
> in the future, they are clean cherry-picks (besides simple context changes)
> and we have all the dependencies.
> 
> [Test Plan]
> 
> Ensure CONFIG_CORESIGHT and CONFIG_CORESIGHT_CATU are enabled, then compile test.
> 
> [Where problems could occur]
> 
> There is a low chance of regression because these commits are only small
> refactors that don't change behaviour. Only static function definitions are
> modified, and functionality is only added via new helpers, not removed.
> The new patches have a potential to create conflicts for derivative kernels
> and other downstream projects that rebase on this kernel.
> 
> Anshuman Khandual (3):
>    coresight: stm: Extract device name from AMBA pid based table lookup
>    coresight: tmc: Extract device properties from AMBA pid based table
>      lookup
>    coresight: Add helpers registering/removing both AMBA and platform
>      drivers
> 
>   drivers/hwtracing/coresight/coresight-core.c  | 29 +++++++++++++++++++
>   .../hwtracing/coresight/coresight-funnel.c    | 19 ++----------
>   drivers/hwtracing/coresight/coresight-priv.h  | 10 +++++++
>   .../coresight/coresight-replicator.c          | 20 ++-----------
>   drivers/hwtracing/coresight/coresight-stm.c   | 12 +++++++-
>   .../hwtracing/coresight/coresight-tmc-core.c  | 14 ++++++---
>   include/linux/coresight.h                     |  7 +++++
>   7 files changed, 72 insertions(+), 39 deletions(-)
> 

Rejected for the following reasons:
In this case enabling atclk does not sound like a required bug fix. For 
that reason I would go and rather revert the changes we picked up to 
enable it. Any derivatives that have this driver enabled may choose to 
pull in more changes as they need. Likely there is a better test 
coverage on the driver as well.
So rejecting this submission and waiting for a revert instead. Thanks 
for the work.

-Stefan
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