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Anshuman Khandual 4aff040bcc coresight: etm: Override TRCIDR3.CCITMIN on errata affected cpus
This work arounds errata 1490853 on Cortex-A76, and Neoverse-N1, errata
1491015 on Cortex-A77, errata 1502854 on Cortex-X1, and errata 1619801 on
Neoverse-V1, based affected cpus, where software read for TRCIDR3.CCITMIN
field in ETM gets an wrong value.

If software uses the value returned by the TRCIDR3.CCITMIN register field,
then it will limit the range which could be used for programming the ETM.
In reality, the ETM could be programmed with a much smaller value than what
is indicated by the TRCIDR3.CCITMIN field and still function correctly.

If software reads the TRCIDR3.CCITMIN register field, corresponding to the
instruction trace counting minimum threshold, observe the value 0x100 or a
minimum cycle count threshold of 256. The correct value should be 0x4 or a
minimum cycle count threshold of 4.

This work arounds the problem via storing 4 in drvdata->ccitmin on affected
systems where the TRCIDR3.CCITMIN has been 256, thus preserving cycle count
threshold granularity.

These errata information has been updated in Documentation/arch/arm64/silicon-errata.rst,
but without their corresponding configs because these have been implemented
directly in the driver.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: James Clark <james.clark@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
[ Fixed location of silicon-errata.rst in commit description ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230921033631.1298723-2-anshuman.khandual@arm.com
History 2023-11-16 11:35:01 +00:00
arch parisc architecture fixes for kernel v6.7-rc1 (part 2): 2023-11-12 11:05:31 -08:00
block blk-core: use pr_warn_ratelimited() in bio_check_ro() 2023-11-07 08:15:23 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation coresight: etm: Override TRCIDR3.CCITMIN on errata affected cpus 2023-11-16 11:35:01 +00:00
drivers coresight: etm: Override TRCIDR3.CCITMIN on errata affected cpus 2023-11-16 11:35:01 +00:00
fs Sixteen smb3/cifs client fixes 2023-11-11 17:17:22 -08:00
include Probes fixes for v6.7-rc1: 2023-11-10 16:35:04 -08:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring: do not clamp read length for multishot read 2023-11-06 13:41:58 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel Probes fixes for v6.7-rc1: 2023-11-10 16:35:04 -08:00
lib lib: test_objpool: make global variables static 2023-11-10 19:59:04 +09:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm memblock: report failures when memblock_can_resize is not set 2023-11-08 09:40:13 -08:00
net Including fixes from netfilter and bpf. 2023-11-09 17:09:35 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
security + Features 2023-11-03 09:48:17 -10:00
sound sound fixes for 6.7-rc1 2023-11-10 11:57:51 -08:00
tools LoongArch changes for v6.7 2023-11-12 10:58:08 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Remove myself as a Arm CoreSight reviewer 2023-11-16 11:34:52 +00:00
Makefile Linux 6.7-rc1 2023-11-12 16:19:07 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.