Claude review: Add DRM driver for Solomon SSD16xx e-paper display controllers

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

Overall Series Review

Subject: Add DRM driver for Solomon SSD16xx e-paper display controllers
Author: Devarsh Thakkar <devarsht@ti.com>
Patches: 9
Reviewed: 2026-05-05T10:10:09.684993

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This is a well-structured 6-patch series adding a new DRM driver for the Solomon SSD16xx e-paper display controller family. The driver is feature-rich and well-documented, with hardware rotation, multiple refresh modes, 3-colour support, runtime PM, and extensive configurability. That said, there are several architectural concerns and some bugs that should be addressed before merging:

1. **The driver is very large for `drm/tiny`** at ~2730 lines. The amount of custom connector properties, module parameters, and policy logic (clear-on-init, clear-on-close, clear-on-disable, refresh-mode-init, border waveform management) goes well beyond what "tiny" drivers typically do. Consider whether some of this belongs in userspace policy rather than kernel module parameters.

2. **Custom connector properties are stored directly on the panel struct** rather than in `drm_connector_state`, violating DRM atomic modesetting principles. Property changes take effect immediately rather than being committed atomically.

3. **`master_set`/`master_drop` callbacks are documented as "Only used by vmwgfx"** in `drm_drv.h`. Using them for per-client init/clear logic is non-standard and should be discussed with DRM maintainers. Consider whether `drm_client` infrastructure or fbdev integration would be a better fit.

4. **RGB888 pixel extraction has swapped R/B channels** -- a correctness bug in `ssd16xx_pixel_luma()` and `ssd16xx_pixel_is_red()`.

5. **The number of module parameters is excessive.** Ten module parameters that duplicate DRM connector properties adds maintenance burden. Module parameters are generally discouraged for new DRM drivers; DRM properties alone should be sufficient.

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