[FS#111] [ath9k] Commit 207338c causes WiFi performance regression(160MBit -> 45MBit)

[LEDE Bugs]

The following task has a new comment added:

FS#111 - [ath9k] Commit 207338c causes WiFi performance regression(160MBit -> 45MBit)
User who did this - Zhong Jianxin (azuwis)

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Tested with git revision 02e3c71(r1455), WiFi performance was good, rx 186 Mbits/sec, tx 150 Mbits/sec.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=111#comment320