Claude review: drm/msm: Add PERFCNTR_CONFIG ioctl

[Claude Code Review Bot <claude-review@example.com>]

Overall Series Review

Subject: drm/msm: Add PERFCNTR_CONFIG ioctl
Author: Rob Clark <robin.clark@oss.qualcomm.com>
Patches: 17
Reviewed: 2026-05-25T18:21:38.448846

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This is a well-structured v9 series adding a `PERFCNTR_CONFIG` ioctl to the MSM DRM driver for Adreno GPU performance counter collection. The series is logically ordered: first remove the old perf infrastructure, add register definitions and tables, build up infrastructure incrementally, add the ioctl, then wire up IFPC support. The design separating global counter streaming (privileged, via fd) from local counter reservation (unprivileged, per-context) is clean. The locking is carefully thought out with good comments explaining the reasoning (especially the sel_work cancellation dance). This is v9, so it has had extensive review, and the changelogs show many issues already caught by both human reviewers and automated review (Claude).

The most notable issue I found is a missing `-EAGAIN` return in the stream read path for `O_NONBLOCK`. There are also some minor style and robustness observations. The patches are well-reviewed (R-b from Dmitry, Anna, and Akhil on most patches).

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