[FS#295] ath10k_pci 0001:01:00.0: SWBA overrun on vdev

[LEDE Bugs]

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FS#295 - ath10k_pci 0001:01:00.0: SWBA overrun on vdev
User who did this - Ian MacDonald (imac)

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We have several ArcherC7s that experience periodic disconnect on 2.4G band. We are fairly certain it occurs on all of them. And we do see this SWBA message, though not in direct correlation with each failure of the 2.4G.  

The result is no 2.4G devices can connect (no issue with 5G) until we execute "wifi" or reboot the ArcherC7s. 

We have applied a cron job that runs each night and executes "wifi" to workaround this issue since 17.01.2 but believe it may have been present since 17.01.1.  It is still present in 17.01.4 unfortunately, so we are confident that this is no transient bug, so will begin posting to try and resolve. 

In on of our office locations, to monitor this bug with the hope of oneday resolving it, we do not run the cron job, and only have two 2.4G devices connected.  

In the last 52 days, the 2.4G failure happenened three times.  Between the 1st and 2nd occurence we saw these similar SWBA  messages in our dmesg. Could be related to this ticket, so we have provided those details here. 

[2506537.784853] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02100020 DMADBG_7=0x00028800
[2506539.854485] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.862178] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.869849] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.877511] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.885148] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.892821] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.900499] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.908171] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.915809] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
[2506539.923492] ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon

Before each occurence at some point we see these messages:

[290147.737347] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0
[463582.984526] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0

[2794383.390501] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0
[2794532.486186] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0

[4541364.695287] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0
[4541500.990587] ath10k_pci 0000:01:00.0: failed to parse phyerr tlv payload at byte 0

Since there is not much else in the dmesg, other then the bridge changes, when we execute "wifi" to resolve the issue, it is pretty easy to surmize that these messages are related to our dropping of 2.4G as they seem to be present before the bridge messages that occur when we resolve the problem.   

The 2.4G clients are a D-LINK DCH-S150 motion detector (70:62:b8:93:98:b8) and a Google Chromecast (6C:AD:F8:4B:A3:52)
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=295#comment4083