This is a note to let you know that I've just added the patch titled
ath9k_hw: fix stopping rx DMA during resets
to the 2.6.38-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ath9k_hw-fix-stopping-rx-dma-during-resets.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 5882da02e9d9089b7e8c739f3e774aaeeff8b7ba Mon Sep 17 00:00:00 2001
From: Felix Fietkau <[email protected]>
Date: Fri, 8 Apr 2011 20:13:18 +0200
Subject: ath9k_hw: fix stopping rx DMA during resets
From: Felix Fietkau <[email protected]>
commit 5882da02e9d9089b7e8c739f3e774aaeeff8b7ba upstream.
During PHY errors, the MAC can sometimes fail to enter an idle state on older
hardware (before AR9380) after an rx stop has been requested.
This typically shows up in the kernel log with messages like these:
ath: Could not stop RX, we could be confusing the DMA engine when we start RX up
------------[ cut here ]------------
WARNING: at drivers/net/wireless/ath/ath9k/recv.c:504 ath_stoprecv+0xcc/0xf0
[ath9k]()
Call Trace:
[<8023f0e8>] dump_stack+0x8/0x34
[<80075050>] warn_slowpath_common+0x78/0xa4
[<80075094>] warn_slowpath_null+0x18/0x24
[<80d66d60>] ath_stoprecv+0xcc/0xf0 [ath9k]
[<80d642cc>] ath_set_channel+0xbc/0x270 [ath9k]
[<80d65254>] ath_radio_disable+0x4a4/0x7fc [ath9k]
When this happens, the state that the MAC enters is easy to identify and
does not result in bogus DMA traffic, however to ensure a working state
after a channel change, the hardware should still be reset.
This patch adds detection for this specific MAC state, after which the above
warnings completely disappear in my tests.
Signed-off-by: Felix Fietkau <[email protected]>
Cc: Kyungwan Nam <[email protected]>
Signed-off-by: John W. Linville <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/wireless/ath/ath9k/hw.c | 9 ---------
drivers/net/wireless/ath/ath9k/mac.c | 25 ++++++++++++++++++++++---
drivers/net/wireless/ath/ath9k/mac.h | 2 +-
drivers/net/wireless/ath/ath9k/recv.c | 6 +++---
4 files changed, 26 insertions(+), 16 deletions(-)
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1218,15 +1218,6 @@ int ath9k_hw_reset(struct ath_hw *ah, st
ah->txchainmask = common->tx_chainmask;
ah->rxchainmask = common->rx_chainmask;
- if ((common->bus_ops->ath_bus_type != ATH_USB) && !ah->chip_fullsleep) {
- ath9k_hw_abortpcurecv(ah);
- if (!ath9k_hw_stopdmarecv(ah)) {
- ath_dbg(common, ATH_DBG_XMIT,
- "Failed to stop receive dma\n");
- bChannelChange = false;
- }
- }
-
if (!ath9k_hw_setpower(ah, ATH9K_PM_AWAKE))
return -EIO;
--- a/drivers/net/wireless/ath/ath9k/mac.c
+++ b/drivers/net/wireless/ath/ath9k/mac.c
@@ -770,28 +770,47 @@ void ath9k_hw_abortpcurecv(struct ath_hw
}
EXPORT_SYMBOL(ath9k_hw_abortpcurecv);
-bool ath9k_hw_stopdmarecv(struct ath_hw *ah)
+bool ath9k_hw_stopdmarecv(struct ath_hw *ah, bool *reset)
{
#define AH_RX_STOP_DMA_TIMEOUT 10000 /* usec */
#define AH_RX_TIME_QUANTUM 100 /* usec */
struct ath_common *common = ath9k_hw_common(ah);
+ u32 mac_status, last_mac_status = 0;
int i;
+ /* Enable access to the DMA observation bus */
+ REG_WRITE(ah, AR_MACMISC,
+ ((AR_MACMISC_DMA_OBS_LINE_8 << AR_MACMISC_DMA_OBS_S) |
+ (AR_MACMISC_MISC_OBS_BUS_1 <<
+ AR_MACMISC_MISC_OBS_BUS_MSB_S)));
+
REG_WRITE(ah, AR_CR, AR_CR_RXD);
/* Wait for rx enable bit to go low */
for (i = AH_RX_STOP_DMA_TIMEOUT / AH_TIME_QUANTUM; i != 0; i--) {
if ((REG_READ(ah, AR_CR) & AR_CR_RXE) == 0)
break;
+
+ if (!AR_SREV_9300_20_OR_LATER(ah)) {
+ mac_status = REG_READ(ah, AR_DMADBG_7) & 0x7f0;
+ if (mac_status == 0x1c0 && mac_status ==
last_mac_status) {
+ *reset = true;
+ break;
+ }
+
+ last_mac_status = mac_status;
+ }
+
udelay(AH_TIME_QUANTUM);
}
if (i == 0) {
ath_err(common,
- "DMA failed to stop in %d ms AR_CR=0x%08x
AR_DIAG_SW=0x%08x\n",
+ "DMA failed to stop in %d ms AR_CR=0x%08x
AR_DIAG_SW=0x%08x DMADBG_7=0x%08x\n",
AH_RX_STOP_DMA_TIMEOUT / 1000,
REG_READ(ah, AR_CR),
- REG_READ(ah, AR_DIAG_SW));
+ REG_READ(ah, AR_DIAG_SW),
+ REG_READ(ah, AR_DMADBG_7));
return false;
} else {
return true;
--- a/drivers/net/wireless/ath/ath9k/mac.h
+++ b/drivers/net/wireless/ath/ath9k/mac.h
@@ -692,7 +692,7 @@ bool ath9k_hw_setrxabort(struct ath_hw *
void ath9k_hw_putrxbuf(struct ath_hw *ah, u32 rxdp);
void ath9k_hw_startpcureceive(struct ath_hw *ah, bool is_scanning);
void ath9k_hw_abortpcurecv(struct ath_hw *ah);
-bool ath9k_hw_stopdmarecv(struct ath_hw *ah);
+bool ath9k_hw_stopdmarecv(struct ath_hw *ah, bool *reset);
int ath9k_hw_beaconq_setup(struct ath_hw *ah);
/* Interrupt Handling */
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -513,12 +513,12 @@ start_recv:
bool ath_stoprecv(struct ath_softc *sc)
{
struct ath_hw *ah = sc->sc_ah;
- bool stopped;
+ bool stopped, reset = false;
spin_lock_bh(&sc->rx.rxbuflock);
ath9k_hw_abortpcurecv(ah);
ath9k_hw_setrxfilter(ah, 0);
- stopped = ath9k_hw_stopdmarecv(ah);
+ stopped = ath9k_hw_stopdmarecv(ah, &reset);
if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
ath_edma_stop_recv(sc);
@@ -533,7 +533,7 @@ bool ath_stoprecv(struct ath_softc *sc)
"confusing the DMA engine when we start RX up\n");
ATH_DBG_WARN_ON_ONCE(!stopped);
}
- return stopped;
+ return stopped || reset;
}
void ath_flushrecv(struct ath_softc *sc)
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.38/ath9k_hw-fix-stopping-rx-dma-during-resets.patch
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