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i2c-imc-skylake: split the submission into a PCI patch and the driver

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The driver reached the PCU function's config space by walking the ACPI MCFG
table and mapping the ECAM page itself. That is one leaf driver deciding
config-space policy, and no other driver in mainline does it, so it was the
single most likely reason for a NAK.

Move that decision where it belongs: the upstream series is now two patches,
a PCI/x86 accessor that forces the memory-mapped path with the core's
locking, and this driver on top of it. Reviewers on each side now get
something they can act on, and get_maintainer.pl selects the PCI and x86
people by itself.

Correctness work in the same pass:

  - the completion bits are latched, so a command the engine never accepted
    was indistinguishable from a completed one and returned the previous
    transaction's data as valid. Require a positive sign that the engine
    acted on the command;
  - compare the command registers after every transfer against what the
    driver left in them and fail with -EAGAIN on a mismatch. The original
    iMC driver had this check and it is what makes an unarbitrated system
    detectable instead of silently wrong;
  - use the i2c core's suspended-adapter mechanism rather than a private
    flag and -EHOSTDOWN;
  - use devm_mutex_init(), drop the unnecessary pci_enable_device(), and
    return -ENODEV rather than -EPERM from the default-off gate, which was
    printing a driver-core error on every boot;
  - mask GO when restoring a saved command word.

Stop attributing the dropped CF8/CFC write to System Management Mode. The
only evidence was a boot log line naming the access method, which says
nothing about who filters the write. tools/probe-cf8-write.sh is there to
settle it with an MSR_SMI_COUNT measurement.

Add Documentation/i2c/busses/i2c-imc-skylake.rst, which every other PC SMBus
driver has and which was explicitly asked for on the 2020 iMC thread, the
tools/ scripts for the hardware measurements the submission still owes, and
compat/pci-mmcfg-compat.h so the driver still builds out-of-tree against a
kernel without the new accessor while the source stays byte-identical to the
submitted patch.
This commit is contained in:
Simone
2026-07-26 19:27:14 +02:00
parent e9a90d63ac
commit 3cd1d6e0a6
18 changed files with 2026 additions and 560 deletions
Download Patch File Download Diff File Expand all files Collapse all files
.github/workflows/ci.yml
+124 -6
View File
@@ -9,14 +9,31 @@ on:
- main
workflow_dispatch:
permissions:
contents: read
concurrency:
group: ci-${{ github.ref }}
cancel-in-progress: true
env:
I2C_TREE: https://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git
SPARSE_REPOSITORY: https://git.kernel.org/pub/scm/devel/sparse/sparse.git
SPARSE_COMMIT: 00c4b8e75cbf92003bc4a695a223045092b173f3
jobs:
build:
out-of-tree:
name: Out-of-tree (${{ matrix.compiler }})
runs-on: ubuntu-latest
timeout-minutes: 30
strategy:
fail-fast: false
matrix:
include:
- compiler: gcc
make_args: ""
- compiler: clang
make_args: LLVM=1
steps:
- uses: actions/checkout@v4
@@ -24,20 +41,121 @@ jobs:
- name: Install build dependencies
run: |
sudo apt-get update
sudo apt-get install -y build-essential linux-headers-$(uname -r)
sudo apt-get install -y build-essential clang llvm linux-headers-$(uname -r)
# A stock kernel has no pci_mmcfg_read_config() yet, so this exercises
# the compat/ shim path. The in-tree job below covers the real thing.
- name: Build module
run: make
run: make W=1 KCFLAGS=-W ${{ matrix.make_args }}
- name: Run checkpatch
if: matrix.compiler == 'gcc'
run: make checkpatch
- name: Check shell scripts
if: matrix.compiler == 'gcc'
run: |
curl -sSLo checkpatch.pl https://raw.githubusercontent.com/torvalds/linux/master/scripts/checkpatch.pl
curl -sSLo spelling.txt https://raw.githubusercontent.com/torvalds/linux/master/scripts/spelling.txt
perl checkpatch.pl --no-tree --strict --no-summary --show-types -f i2c-imc-skylake.c
sudo apt-get install -y shellcheck
bash -n test-smoke.sh
for f in tools/*.sh; do bash -n "$f"; done
shellcheck -S warning test-smoke.sh tools/*.sh
- name: Upload artifact
if: matrix.compiler == 'gcc'
uses: actions/upload-artifact@v4
with:
name: i2c-imc-skylake-${{ github.ref_name }}
path: i2c-imc-skylake.ko
if-no-files-found: error
in-tree:
name: Current i2c-host integration (2-patch series)
runs-on: ubuntu-latest
timeout-minutes: 45
steps:
- uses: actions/checkout@v4
- name: Install kernel build dependencies
run: |
sudo apt-get update
sudo apt-get install -y bc bison build-essential clang flex libelf-dev libssl-dev llvm
- name: Build pinned Sparse
run: |
git clone --filter=blob:none "$SPARSE_REPOSITORY" sparse
git -C sparse checkout "$SPARSE_COMMIT"
make -C sparse -j"$(nproc)"
echo "$PWD/sparse" >> "$GITHUB_PATH"
- name: Prepare current maintainer tree
run: |
git clone --depth=1 --branch i2c/i2c-host "$I2C_TREE" linux-i2c
# Patch 1/2: the PCI/x86 accessor the driver depends on. If this
# stops applying, the tracked copy is stale and must be refreshed
# from the kernel tree - that is a real failure, not CI noise.
git -C linux-i2c apply --verbose \
../docs/submission/0001-pci-mmcfg-accessor.patch
# Patch 2/2: the driver itself.
cp i2c-imc-skylake.c linux-i2c/drivers/i2c/busses/
cat docs/submission/Kconfig.kernel >> linux-i2c/drivers/i2c/busses/Kconfig
printf '%s\n' 'obj-$(CONFIG_I2C_IMC_SKYLAKE) += i2c-imc-skylake.o' \
>> linux-i2c/drivers/i2c/busses/Makefile
git -C linux-i2c rev-parse HEAD
- name: Configure kernel
working-directory: linux-i2c
run: |
make O=../linux-out x86_64_defconfig
scripts/config --file ../linux-out/.config --enable I2C --module I2C_IMC_SKYLAKE
make O=../linux-out olddefconfig
grep '^CONFIG_I2C_IMC_SKYLAKE=m' ../linux-out/.config
grep '^CONFIG_PCI_MMCONFIG=y' ../linux-out/.config
- name: Build the series in-tree
working-directory: linux-i2c
run: |
make O=../linux-out W=1 \
drivers/pci/access.o \
arch/x86/pci/mmconfig-shared.o \
drivers/i2c/busses/i2c-imc-skylake.o
- name: Build arm64 COMPILE_TEST with Clang
working-directory: linux-i2c
run: |
make O=../linux-out-arm64 ARCH=arm64 LLVM=1 defconfig
scripts/config --file ../linux-out-arm64/.config \
--enable COMPILE_TEST --enable PCI --enable I2C \
--module I2C_IMC_SKYLAKE
make O=../linux-out-arm64 ARCH=arm64 LLVM=1 olddefconfig
grep '^CONFIG_I2C_IMC_SKYLAKE=m' ../linux-out-arm64/.config
make O=../linux-out-arm64 ARCH=arm64 LLVM=1 W=1 \
drivers/pci/access.o \
drivers/i2c/busses/i2c-imc-skylake.o
- name: Run Sparse in-tree
working-directory: linux-i2c
run: |
make O=../linux-out C=2 CF=-D__CHECK_ENDIAN__ \
drivers/pci/access.o \
arch/x86/pci/mmconfig-shared.o \
drivers/i2c/busses/i2c-imc-skylake.o
- name: Run current-tree checkpatch
working-directory: linux-i2c
run: |
scripts/checkpatch.pl --strict --no-tree -f \
drivers/i2c/busses/i2c-imc-skylake.c
scripts/checkpatch.pl --strict \
../docs/submission/0001-pci-mmcfg-accessor.patch
- name: Build the documentation
working-directory: linux-i2c
run: |
sudo apt-get install -y python3-sphinx python3-sphinx-rtd-theme
cp ../docs/submission/i2c-imc-skylake.rst Documentation/i2c/busses/
sed -i 's|^ i2c-i801$| i2c-i801\n i2c-imc-skylake|' \
Documentation/i2c/busses/index.rst
grep -q i2c-imc-skylake Documentation/i2c/busses/index.rst
make O=../linux-out htmldocs SPHINXDIRS=i2c 2>&1 | tee doc.log | tail -20
! grep -Ei 'WARNING|ERROR' doc.log