Claude review: drm/sitronix/st7586: fix bad pixel data due to byte swap

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

Patch Review

**Correctness: Good**

The fix correctly sets `dbi->write_memory_bpw = 8` immediately after `mipi_dbi_spi_init()`, which defaults `write_memory_bpw` to 16. This is the right value for the ST7586 since it uses 8-bit data (3 grayscale pixels packed per byte). The placement is correct:

1. `mipi_dbi_spi_init()` sets `write_memory_bpw = 16` (default)
2. **Patch adds** `dbi->write_memory_bpw = 8` — overrides before anything else uses the value
3. `mipi_dbi_dev_init_with_formats()` only overrides `write_memory_bpw` for `DRM_FORMAT_RGB888`, but st7586 uses `DRM_FORMAT_XRGB8888`, so no conflict

```c
+	/*
+	 * Override value set by mipi_dbi_spi_init(). This driver is a bit
+	 * non-standard, so best to set it explicitly here.
+	 */
+	dbi->write_memory_bpw = 8;
```

**Removal of old workaround: Correct**

The old `swap_bytes = true` block is properly removed. The old comment explained that `swap_bytes` was being used not for actual byte swapping, but to trick `mipi_dbi_typec3_command()` into using 8-bit SPI transfers. That mechanism is now replaced by the direct `write_memory_bpw` control:

```c
-	/*
-	 * we are using 8-bit data, so we are not actually swapping anything,
-	 * but setting mipi->swap_bytes makes mipi_dbi_typec3_command() do the
-	 * right thing and not use 16-bit transfers (which results in swapped
-	 * bytes on little-endian systems and causes out of order data to be
-	 * sent to the display).
-	 */
-	dbi->swap_bytes = true;
```

**Minor style observation (not blocking):** The new comment is slightly generic — "a bit non-standard" doesn't explain *why* 8 bpw is needed. The old comment was more informative about the root cause (3 pixels per byte, 8-bit data). A one-liner like "ST7586 uses 8-bit data (3 pixels per byte)" would be more helpful to future readers. But this is a nit.

**Commit message: Good.** Clear explanation of the problem (every 3 columns swapped), root cause (default 16-bit transfers after refactoring), and fix. Proper `Fixes:` tag referencing the breaking commit.

**No other concerns.** The patch is minimal, focused, and correct.

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