[Bug 192415] New: [ath] AR933x power save causes the AR9331 to stop DMA

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=192415

            Bug ID: 192415
           Summary: [ath] AR933x power save causes the AR9331 to stop DMA
           Product: Base System
           Version: 11.0-CURRENT
          Hardware: Any
                OS: Any
            Status: Needs Triage
          Severity: Affects Only Me
          Priority: ---
         Component: wireless
          Assignee: freebsd-wireless at FreeBSD.org
          Reporter: adrian at freebsd.org

The current powersave code in the ath(4) driver / HAL is causing issues on the
AR9331.

Even if powersave is disabled, the chip is put into powersave mode when no VAPs
are in use. This seems to lock up the DMA side of things.

Symptoms:

* lots of "disable rx dma failed" messages
* no packets being transmitted/received
* TX/RX interrupt counts don't increase
* if AH_INTERRUPT_DEBUGGING is defined, then sync interrupts are posted - 0x200
and 0x40.

Now, I'm not sure yet what those bits are. I guess it's similar to the AR9340
ones - AR9340_INTR_SYNC_MAC_SLEEP_ACCESS (0x40). That meant that it was
configured whilst the MAC was asleep. Ugh.

If i disable the power save code in if_ath.c (ie, make all the
ath_hal_setpowermode() calls to HAL_PM_AWAKE) then things work fine.

So, figure out what is being programmed whilst the MAC is asleep, or what is
currently not shut down correctly before the MAC is put to sleep.

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