[FS#896] mt7620 - dropping frames (WiFi)

[LEDE Bugs]

The following task has a new comment added:

FS#896 - mt7620 - dropping frames (WiFi)
User who did this - psyborg55 (psyborg55)

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one series of 6 warnings, connection still worked:

[198938.155172] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[198938.164724] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[198938.174261] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[198938.183791] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[198938.193330] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[198938.202841] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2

another series of 6 warnings, connection still worked:

[203162.530970] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[203162.540538] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[203162.550077] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[203162.559606] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[203162.569139] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[203162.578652] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2

one series of 3 warnings, connection still worked:

[214232.780698] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[214232.790263] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2
[214232.799800] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2

1 warning, connectivity lost:

[216186.446237] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Dropping frame due to full tx queue 2

change channel, mode to legacy or disable/enable interface result in following rt2x00queue_write_tx_frame error:

[216922.802626] ieee80211 phy1: rt2x00queue_flush_queue: Warning - Queue 2 failed to flush
[216923.173465] ieee80211 phy1: rt2x00queue_flush_queue: Warning - Queue 2 failed to flush
[216925.366648] ieee80211 phy1: rt2800_rf_self_txdc_cal: Info - RF Tx self calibration start
[216925.393555] ieee80211 phy1: rt2800_rf_self_txdc_cal: Info - RF Tx self calibration end
[216930.067469] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=156, sq=153, riq=-1, bbpval 156, vga_idx 0
[216930.080310] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=5212, sq=5137, riq=75, bbpval 5212, vga_idx 8
[216930.093508] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=8064, sq=7946, riq=139, bbpval 8064, vga_idx 9
[216930.106625] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=12201, sq=12002, riq=226, bbpval 12201, vga_idx 10
[216930.117672] ieee80211 phy1: rt2800_rxiq_calibration: Info - Sigma_i=1104, Sigma_q=1095, R_iq=2260
[216930.126840] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ Sigma_i=1104, Sigma_q=1095, R_iq=2260
[216930.136442] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ G_imb=-1, Ph_rx=4
[216930.147781] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=78, sq=79, riq=1, bbpval 78, vga_idx 0
[216930.160173] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=4189, sq=4263, riq=45, bbpval 4189, vga_idx 9
[216930.173204] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ si=6349, sq=6470, riq=54, bbpval 6349, vga_idx 10
[216930.183901] ieee80211 phy1: rt2800_rxiq_calibration: Info - Sigma_i=796, Sigma_q=804, R_iq=540
[216930.192805] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ Sigma_i=796, Sigma_q=804, R_iq=540
[216930.202135] ieee80211 phy1: rt2800_rxiq_calibration: Info - RXIQ calibration FAIL
[216936.308202] ieee80211 phy1: rt2x00queue_write_tx_frame: Error - Arrived at non-free entry in the non-full queue 2
[216936.308202] Please file bug report to http://rt2x00.serialmonkey.com

when took several bandwidth tests with android phone they all show full speed without any warnings or messages in logs
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=896#comment2992