Date: Sun, 31 Jul 2011 16:16:25 +0000 (UTC) From: Adrian Chadd <adrian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r224550 - head/sys/dev/ath Message-ID: <201107311616.p6VGGPHI053909@svn.freebsd.org>
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Author: adrian Date: Sun Jul 31 16:16:25 2011 New Revision: 224550 URL: http://svn.freebsd.org/changeset/base/224550 Log: Disable the RXORN/RXEOL interrupts if RXEOL occurs, preventing an interrupt storm. This is easily triggered by flipping on and off tcpdump -y IEEE802_11_RADIO w/ witness enabled. This causes a whole lot of console IO and when you're attached to a serial console (eg on my AR7161 embedded board), the RX interrupt doesn't get called quickly enough and the RX queue fills up. This wasn't a problem in the past because of the self-linked RX descriptor trick - the RX would never hit the "end" of the RX descriptor list. However this isn't possible for 802.11n (see previous commit history for why.) Both Linux ath9k and the Atheros reference driver code do this; I'm just looking now for where they then restart the PCU receive. Right now the RX will just stop until the interface is reset. Obtained from: Linux, Atheros Approved by: re (kib) Modified: head/sys/dev/ath/if_ath.c Modified: head/sys/dev/ath/if_ath.c ============================================================================== --- head/sys/dev/ath/if_ath.c Sun Jul 31 16:08:29 2011 (r224549) +++ head/sys/dev/ath/if_ath.c Sun Jul 31 16:16:25 2011 (r224550) @@ -1395,6 +1395,12 @@ ath_intr(void *arg) * least on older hardware revs. */ sc->sc_stats.ast_rxeol++; + /* + * Disable RXEOL/RXORN - prevent an interrupt + * storm until the PCU logic can be reset. + */ + sc->sc_imask &= ~(HAL_INT_RXEOL | HAL_INT_RXORN); + ath_hal_intrset(ah, sc->sc_imask); sc->sc_rxlink = NULL; } if (status & HAL_INT_TXURN) {
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