On 2011-03-15 9:51 PM, Luis R. Rodriguez wrote: > On Tue, Mar 08, 2011 at 05:15:41PM -0800, Felix Fietkau wrote: >> On 2011-03-09 2:07 AM, Ben Greear wrote: >> > On 03/08/2011 04:48 PM, Felix Fietkau wrote: >> >> The hardware rx filter flag triggered by FIF_PROMISC_IN_BSS is overly broad >> >> and covers even frames with PHY errors. When this flag is enabled, this message >> >> shows up frequently during scanning or hardware resets: >> >> >> >> ath: Could not stop RX, we could be confusing the DMA engine when we start RX up >> >> >> >> Since promiscuous mode is usually not particularly useful, yet enabled by >> >> default by bridging (either used normally in 4-addr mode, or with hacks >> >> for various virtualization software), we should sacrifice it for better >> >> reliability during normal operation. >> >> >> >> This patch leaves it enabled if there are active monitor mode interfaces, since >> >> it's very useful for debugging. >> >> >> >> Signed-off-by: Felix Fietkau<nbd@xxxxxxxxxxx> >> >> Cc: stable@xxxxxxxxxx >> >> --- >> >> drivers/net/wireless/ath/ath9k/recv.c | 4 +--- >> >> 1 files changed, 1 insertions(+), 3 deletions(-) >> >> >> >> diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c >> >> index cb559e3..a9c3f46 100644 >> >> --- a/drivers/net/wireless/ath/ath9k/recv.c >> >> +++ b/drivers/net/wireless/ath/ath9k/recv.c >> >> @@ -413,9 +413,7 @@ u32 ath_calcrxfilter(struct ath_softc *sc) >> >> * mode interface or when in monitor mode. AP mode does not need this >> >> * since it receives all in-BSS frames anyway. >> >> */ >> >> - if (((sc->sc_ah->opmode != NL80211_IFTYPE_AP)&& >> >> - (sc->rx.rxfilter& FIF_PROMISC_IN_BSS)) || >> >> - (sc->sc_ah->is_monitoring)) >> >> + if (sc->sc_ah->is_monitoring) >> >> rfilt |= ATH9K_RX_FILTER_PROM; >> >> >> >> if (sc->rx.rxfilter& FIF_CONTROL) >> > >> > Should we enable this flag if we have multiple STA >> > interfaces? I had to add something to ath5k recently >> > to put it into promisc to properly handle multiple STAs >> > associated with different APs, for instance. >> No, multiple interfaces is handled by the BSSID mask. >> >> > Do you have any idea *why* enabling this flag causes the DMA error >> > messages? >> I don't know why exactly it happens, but it probably cannot be explained >> without going to the details of the inner workings of the MAC/baseband >> interaction. But as I mentioned in the description, this flag is overly >> broad and doesn't just bypass the address match, but lets all kinds of >> other crap through as well - in many situations where even 'normal' >> promiscuous behavior would be completely useless. >> I think because of that, disabling it for non-monitor operation is the >> right thing to do. > > Nice find, thanks for looking at this. Are we cured now from all of > these rants? Or has anyone seem more? There is definitely more. While this does reduce the occurences of the DMA RX failure a lot, it neither fixes the root cause of this issue, nor handles the case where a monitor mode interface is configured. To fix the issue properly, we need more input from the hw guys. - Felix -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
