Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932604Ab1D2S6I (ORCPT ); Fri, 29 Apr 2011 14:58:08 -0400 Received: from kroah.org ([198.145.64.141]:50145 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753090Ab1D2S6E (ORCPT ); Fri, 29 Apr 2011 14:58:04 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Apr 29 11:56:52 2011 Message-Id: <20110429185652.677904385@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 29 Apr 2011 11:55:24 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Felix Fietkau , Kyungwan Nam , "John W. Linville" Subject: [01/55] ath9k_hw: fix stopping rx DMA during resets In-Reply-To: <20110429185706.GA12824@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5334 Lines: 158 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Felix Fietkau 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 Cc: Kyungwan Nam Signed-off-by: John W. Linville Signed-off-by: Greg Kroah-Hartman --- 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/