[ 3.5.y.z extended stable ] Patch "ath9k_hw: improve reset reliability after errors" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ath9k_hw: improve reset reliability after errors

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From a20f4a2c6ad23869628a1ba93b8210e4bebee9af Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd at openwrt.org>
Date: Mon, 25 Feb 2013 20:51:07 +0100
Subject: [PATCH] ath9k_hw: improve reset reliability after errors

commit 3412f2f086ea7531378fabe756bd4a1109994ae6 upstream.

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.

Signed-off-by: Felix Fietkau <nbd at openwrt.org>
Signed-off-by: John W. Linville <linville at tuxdriver.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wireless/ath/ath9k/hw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 988b1f3..6333166 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1472,7 +1472,9 @@ 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;
--
1.8.1.2