ath9k_hw: improve reset reliability after errors

On many different chips, important aspects of the MAC state are not
fully cleared by a warm reset. This can show up as tx/rx hangs, those
annoying "DMA failed to stop in 10 ms..." messages or other quirks.

On AR933x, the chip can occasionally get stuck in a way that only a
driver unload/reload or a reboot would bring it back to life.

With this patch, a full reset is issued when bringing the chip out of
FULL-SLEEP state (after idle), or if either Rx or Tx was not shut down
properly. This makes the DMA related error messages disappear completely
in my tests on AR933x, and the chip does not get stuck anymore.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 42cf3c7f1e25bd29b23ec1c64dad10339b4d2416..7b485e4d104cdfb2f6dd584d2f97e0a2e229cf6e 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1463,7 +1463,9 @@ static bool ath9k_hw_chip_reset(struct ath_hw *ah,
                        reset_type = ATH9K_RESET_POWER_ON;
                else
                        reset_type = ATH9K_RESET_COLD;
-       }
+       } else if (ah->chip_fullsleep || REG_READ(ah, AR_Q_TXE) ||
+                  (REG_READ(ah, AR_CR) & AR_CR_RXE))
+               reset_type = ATH9K_RESET_COLD;
 
        if (!ath9k_hw_set_reset_reg(ah, reset_type))
                return false;