Claude review: drm/scdc-helper: Add scdc_status debugfs entry

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

Patch Review

This is the bulk of the series — adds `drm_scdc_read_state`, status flag structs, error counter reading, and the debugfs show function. Generally well done, but a few issues:

**1. Inappropriate comment (medium)**

```c
/* why in the fucking fuck does this return a ssize_t */
ret = drm_scdc_read(connector->ddc, SCDC_ERR_DET_0_L, buf, ARRAY_SIZE(buf));
```

This comment is not appropriate for the kernel tree. If you want to note the type mismatch, something like `/* drm_scdc_read returns ssize_t but 0 on success */` would be acceptable.

**2. Bitfield union portability on big-endian (medium)**

```c
struct drm_scdc_status_flags {
	union {
		struct {
			bool clock_detected : 1;
			bool ch0_locked : 1;
			bool ch1_locked : 1;
			bool ch2_locked : 1;
			...
		} flags __packed;
		u8 data;
	} status0;
```

GCC orders bitfields from LSB on little-endian targets but from MSB on big-endian targets. On a big-endian system, `clock_detected` would map to bit 7 instead of bit 0 (where `SCDC_CLOCK_DETECT` is defined). This means the bitfield-to-register mapping is wrong on big-endian. Consider using explicit bit masks (the header already defines `SCDC_CLOCK_DETECT`, `SCDC_CH0_LOCK`, etc.) and accessor functions instead, or adding an endianness guard/comment explaining why this is acceptable.

**3. Doc typo**

```c
/** @scramling_enabled: true if TMDS scrambling is on */
```

Should be `@scrambling_enabled`.

**4. Status reading clears update flag before reading the register**

In `drm_scdc_read_status0_flags`:
```c
ret = drm_scdc_writeb(connector->ddc, SCDC_UPDATE_0, SCDC_STATUS_UPDATE);
if (ret)
    return ret;

return drm_scdc_readb(connector->ddc, SCDC_STATUS_FLAGS_0, &flags->status0.data);
```

The update flag is cleared (by writing 1 to it) *before* reading the status register. There's a small race window where the sink could update the status between the clear and the read, meaning the source wouldn't know to re-read later. For debugfs this is fine, but since `drm_scdc_read_status0_flags` is exported as a general-purpose API, consider documenting this behavior or swapping the order (read first, then clear). The same pattern appears in `drm_scdc_read_error_counters` with `SCDC_CED_UPDATE`, though for CED clearing before reading is the spec-mandated behavior, so that one is correct.

**5. Minor: `status1` bitfields are all reserved and unused**

The `status1` member in `drm_scdc_status_flags` has 8 reserved bool bitfields but is never read or displayed in this patch. This is fine since patch 3 replaces them, but in isolation patch 1 adds dead code.

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