[FS#473] ath9k unstable - kernel panic every ~5 minutes

[LEDE Bugs]

The following task has a new comment added:

FS#473 - ath9k unstable - kernel panic every ~5 minutes
User who did this - Mauro Mozzarelli (ezplanet)

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This task appears to be related to Task #471 occurring on BT Home Hub 5 when configured for SMP.
Disabling ATF as suggested above appears to resolve BT Home Hub 5 crashing (no more crashes)
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=473#comment1676