Arm backend: Fixup and make docstrings consistent for key functions

[tom-arm]

• Align formatting across key functions and classes of backend
• Fix some docstrings

Signed-off-by: Tom Allsop [email protected]

Change-Id: I303b01a16cf1fefda3563a49a9937423717903a7

cc @freddan80 @per @zingo @oscarandersson8218 @digantdesai

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15443

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• Long queue for ROCM runners, also B200 and XPU queueing is observed

❌ 1 New Failure, 5 Unrelated Failures

As of commit 7168441 with merge base 94ce147 ():

NEW FAILURE - The following job has failed:

• trunk / test-qnn-model (fp32, w2l) / linux-job (gh)
  RuntimeError: Command docker exec -t 48af74f3e2b132fa85e6f67c93c686c687da2115ad29a689753c420be09b1a42 /exec failed with exit code 56

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• trunk / test-models-windows (emformer_transcribe, portable) / windows-job (gh) (detected as infra flaky with no log or failing log classifier)
• trunk / test-models-windows (resnet50, portable) / windows-job (gh) (detected as infra flaky with no log or failing log classifier)
• trunk / unittest-release / macos / macos-job (gh) (similar failure)
  [ FAILED ] WavLoaderTest.LoadAudioDataRejectsUnsupportedFormat
• trunk / unittest-release / windows / windows-job (gh) (detected as infra flaky with no log or failing log classifier)

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• trunk / unittest-release / linux / linux-job (gh) (trunk failure)
  [ FAILED ] WavLoaderTest.LoadAudioDataRejectsUnsupportedFormat

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[zingo]

1. Fails in test-arm-backedn (xxx)

FAILED backends/arm/test/models/test_conformer.py::test_conformer_tosa_INT - AssertionError: Output 0 does not match reference output.
Given atol: 0.4, rtol: 0.4.
Output tensor shape: torch.Size([10, 93, 16]), dtype: torch.float32
Difference: max: 0.5163156986236572, abs: 0.5163156986236572, mean abs error: 0.019371302803397498.
-- Model vs. Reference --
Numel: 14880, 14880
Median: 0.0, 0.0
Mean: -0.0003138647925469183, -9.620993608428586e-05
Max: 2.9570810794830322, 2.933612108230591
Min: -2.9805498123168945, -2.9805498123168945
= 1 failed, 92 passed, 34 skipped, 13 xfailed, 174 warnings in 1303.03s (0:21:43) =

2. And test-mcu-models
   This is probably fixed with a rebase, Ill retrigger the job