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cpu/stm32/periph_adc: fix register access #20360

Merged
merged 1 commit into from
Feb 8, 2024
Merged

cpu/stm32/periph_adc: fix register access #20360

merged 1 commit into from
Feb 8, 2024

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maribu
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@maribu maribu commented Feb 8, 2024

Contribution description

The register access to SMPR1/SMPR2 was incorrect in three aspects:

  1. For channels < 10, SMPR1 was cleared but SMPR2 should have been cleared
  2. The code was not thread-safe
  3. An unneeded write was issued. (The compiler won't combine the in-place bitwise operations into a single read-modify-write sequence on volatile memory.)

Testing procedure

  • Using ADC lines < 10 should no longer corrupt settings on ADC lines >= 10.
  • Using line x and y with x!=y concurrently should no longer result in race conditions

Issues/PRs references

Fixes #20261

@maribu
cpu/stm32/periph_adc: fix register access
4ed287c 
The register access to SMPR1/SMPR2 was incorrect in three aspects:

1. For channels < 10, SMPR1 was cleared but SMPR2 should have been
   cleared
2. The code was not thread-safe
3. An unneeded write was issued. (The compiler won't combine the
   in-place bitwise operations into a single read-modify-write
   sequence on `volatile` memory.)

Fixes RIOT-OS#20261
@maribu maribu added Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors) CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR labels Feb 8, 2024
@github-actions github-actions bot added Platform: ARM Platform: This PR/issue effects ARM-based platforms Area: cpu Area: CPU/MCU ports labels Feb 8, 2024
@maribu maribu enabled auto-merge February 8, 2024 14:19
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riot-ci commented Feb 8, 2024

Murdock results

✔️ PASSED

4ed287c cpu/stm32/periph_adc: fix register access

Success Failures Total Runtime
10016 0 10016 10m:58s

Artifacts

@maribu maribu added this pull request to the merge queue Feb 8, 2024
@github-merge-queue github-merge-queue bot removed this pull request from the merge queue due to failed status checks Feb 8, 2024
@maribu maribu added this pull request to the merge queue Feb 8, 2024
Merged via the queue into RIOT-OS:master with commit 26946a7 Feb 8, 2024
28 checks passed
@maribu maribu deleted the stm32-adc-typo branch April 23, 2024 08:55
@MrKevinWeiss MrKevinWeiss added this to the Release 2024.04 milestone Apr 30, 2024
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Reviewers

@benpicco benpicco benpicco approved these changes

@aabadie aabadie Awaiting requested review from aabadie aabadie is a code owner

@vincent-d vincent-d Awaiting requested review from vincent-d vincent-d is a code owner

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Area: cpu Area: CPU/MCU ports CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Platform: ARM Platform: This PR/issue effects ARM-based platforms Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors)
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Release 2024.04
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Successfully merging this pull request may close these issues.

STM32 f4_f7 ADC sample time register configuration
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@maribu @riot-ci @benpicco @MrKevinWeiss