ath9k_hw: fix stopping rx DMA during resets

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 <nbd@openwrt.org>
Cc: stable@kernel.org
Cc: Kyungwan Nam <Kyungwan.Nam@Atheros.com>
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 1ec9bcd6b2815c28b34cfd4b2a232c8b055dd716..c95bc5cc1a1fbb4bad3d2e816477c5cfbe96fb97 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1254,15 +1254,6 @@ int ath9k_hw_reset(struct ath_hw *ah, struct ath9k_channel *chan,
        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;
 

diff --git a/drivers/net/wireless/ath/ath9k/mac.c b/drivers/net/wireless/ath/ath9k/mac.c
index 562257ac52cfecf77ee58cd7f1318507f14d9b75..edc1cbbfecaf6fbd153ce00237f1101f49096edc 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/mac.c
+++ b/drivers/net/wireless/ath/ath9k/mac.c
@@ -751,28 +751,47 @@ void ath9k_hw_abortpcurecv(struct ath_hw *ah)
 }
 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;

diff --git a/drivers/net/wireless/ath/ath9k/mac.h b/drivers/net/wireless/ath/ath9k/mac.h
index b2b2ff852c328142a55396801010c46e32c72432..c2a59386fb9cf05a7eabb12214e613103e0c08b0 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/mac.h
+++ b/drivers/net/wireless/ath/ath9k/mac.h
@@ -695,7 +695,7 @@ bool ath9k_hw_setrxabort(struct ath_hw *ah, bool set);
 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 */

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index a9c3f4672aa0e12736a24c8ddb4e4c280d635d29..dcd19bc337d1ddf96890432f085ee6ee83c9658d 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -486,12 +486,12 @@ 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);
@@ -506,7 +506,7 @@ 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)