|WARNING| net/idpf: add clock read support

[dpdklab at iol.unh.edu]

Test-Label: ai-code-review
Test-Status: WARNING
https://dpdk.org/patch/166952

_AI Code Review_

=== Patch Review: series.patch (via Claude) ===
Review date: 2026-07-28

# DPDK Patch Review

## Summary

This patch adds a `read_clock` ethdev operation to the idpf driver by implementing `idpf_dev_read_clock()`. The implementation appears correct but **lacks required documentation updates**.

---

## Findings

### Warnings

**1. Missing Release Notes** (Warning)
The patch adds a new device operation (`read_clock`) but does not update the release notes. New driver features should be documented in the current release notes file (`doc/guides/rel_notes/release_XX_XX.rst`).

**Suggested fix:**
Add an entry to the release notes under the "New Features" or driver-specific section:
```rst
* **Updated idpf driver.**

  * Added support for ``read_clock`` operation to read the device clock
    in nanoseconds for packet scheduling based on transmit time.
```

**2. Missing Features Matrix Update** (Warning)
According to the guidelines, PMD features must match the features matrix in `doc/guides/nics/features/`. The `read_clock` operation should be documented in the idpf driver's feature matrix if this feature is considered a documented capability.

**Suggested fix:**
Update `doc/guides/nics/features/idpf.ini` to reflect the new capability, if applicable. Consult the features documentation (`doc/guides/nics/features.rst`) for the correct feature name mapping.

---

## Code Review

### Correctness
- **No issues found.** The implementation correctly:
  - Retrieves the vport and adapter pointers
  - Delegates to `idpf_ptp_read_src_clk_reg()` which presumably handles the actual hardware read
  - Returns the error code from the underlying function
  - Follows the existing pattern of other timesync operations in the same file

### Style
- **No issues found.** The code follows DPDK coding style:
  - Function naming uses lowercase with underscores
  - Proper indentation and formatting
  - Consistent with surrounding code style
  - No forbidden tokens detected

### API Design
- **No issues found.** The function signature matches the `read_clock` ethdev operation prototype. The operation is correctly added to the `idpf_eth_dev_ops` structure.

---

## Additional Notes

The patch itself is straightforward and correct. The primary concern is the missing documentation updates, which are standard requirements for adding new driver operations. These are **Warnings** rather than **Errors** because they don't affect code correctness, but they should be addressed before merging.