Claude review: fbdev: tdfxfb: avoid divide-by-zero on FBIOPUT_VSCREENINFO

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Patch Review

**Commit message bug — wrong driver name referenced:**

The commit message says:

> we also need to prevent that same crash from happening in the **udlfb** driver as it uses pixclock directly when dividing

But the patch modifies `drivers/video/fbdev/tdfxfb.c`, not `udlfb`. The subject line correctly says `tdfxfb`, but the body references the wrong driver. This is a copy-paste error from what appears to be a templated series fixing the same issue across multiple fbdev drivers. Should be fixed before merging.

**Code change is correct:**

```c
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (PICOS2KHZ(var->pixclock) > par->max_pixclock) {
```

This is the right fix. The guard is placed immediately before the first `PICOS2KHZ(var->pixclock)` call in `tdfxfb_check_var()`, which would divide by zero. Returning `-EINVAL` is the appropriate error code, consistent with other validation failures in the same function.

**Coverage note:** There is a second use of `PICOS2KHZ(info->var.pixclock)` at line 565 in `tdfxfb_set_par()`, but that call path goes through `tdfxfb_check_var()` first (the fbdev core calls `check_var` before `set_par`), so the guard here protects both sites.

**Minor:** The `Assisted-by: gregkh_clanker_t1000` tag is non-standard — the kernel typically uses `Co-developed-by:` or similar recognized tags. Not a blocking issue but worth noting.

**Verdict:** The fix is correct and appropriate for stable. The commit message should be fixed to say "tdfxfb" instead of "udlfb" before applying.

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