On 02/01/2012 08:05 AM, Rajkumar Manoharan wrote:
In the following scenario, where the distance b/w STA and AP is ~10m
or in a shield environment by placing an attenuator with reduced AP
txpower, the station started reporting with beacon loss and got
disconnected whenever the chariot endpoint was initiated with BiDi
traffic. In such state, two different stuck cases were observed.
* rx clear is stuck at low for more than 100ms
* dcu chain and complete state is stuck.
This patch detects the stuck state if the beacons are not received for
more than 300ms. In the above matching conditions, trigger a chip
reset to recover. This issue was originally reported in 3.0 kernel with
AR9382 chip by having two stations associated with two different APs in
the same channel and was attenuated/controlled by Azimuth ADEPT-n box.
Cc: Paul Stewart<pstew@xxxxxxxxxx>
Reported-by: Gary Morain<gmorain@xxxxxxxxxx>
Signed-off-by: Rajkumar Manoharan<rmanohar@xxxxxxxxxxxxxxxx>
Some more comments below.....
+static bool ath9k_check_dcu_chain_state(u32 dma_dbg, int max_limit,
+ int *hang_state, int *hang_pos)
+{
+ static u32 hang_sign[] = {5, 6, 9};
+ u32 chain_state, dcs_pos, i;
+
+ for (dcs_pos = 0; dcs_pos< max_limit; dcs_pos++) {
+ chain_state = (dma_dbg>> (5 * dcs_pos))& 0x1f;
+ for (i = 0; i< 3; i++) {
+ if (chain_state == hang_sign[i]) {
+ *hang_state = chain_state;
+ *hang_pos = dcs_pos;
+ return true;
+ }
+ }
+ }
+ return false;
+}
Perhaps you could add some comments to the code above to describe
what the '5, 6, 9' and other constants mean?
+#define DCU_COMPLETE_STATE 1
+#define NUM_STATUS_READS 50
+static bool ath9k_detect_mac_hang(struct ath_hw *ah)
+{
+ u32 chain_state, comp_state, dcs_reg = AR_DMADBG_4;
+ u32 i, hang_pos, hang_state;
+
+ comp_state = REG_READ(ah, AR_DMADBG_6);
+
+ if ((comp_state& 0x3) != DCU_COMPLETE_STATE) {
+ ath_dbg(ath9k_hw_common(ah), RESET,
+ "MAC Hang signature not found at DCU complete\n");
+ return false;
+ }
Same with the 0x3 (maybe #define what those bits mean and or them together instead
of using the 0x3?)
+
+ chain_state = REG_READ(ah, dcs_reg);
+ if (ath9k_check_dcu_chain_state(chain_state, 6,&hang_state,&hang_pos))
+ goto hang_check_iter;
And why did you choose a '6' here?
+
+ dcs_reg = AR_DMADBG_5;
+ chain_state = REG_READ(ah, dcs_reg);
+ if (ath9k_check_dcu_chain_state(chain_state, 4,&hang_state,&hang_pos))
+ goto hang_check_iter;
And the '4'?
+void ath_start_rx_poll(struct ath_softc *sc, const u32 msec)
+{
+ if (!AR_SREV_9300_20_OR_LATER(sc->sc_ah))
+ return;
+
+ if (!(sc->sc_flags& SC_OP_PRIM_STA_VIF))
+ return;
+
+ mod_timer(&sc->rx_poll_timer, jiffies + msecs_to_jiffies(msec));
+}
Since the rx-poll timer isn't started when SC_OP_PRIM_STA_VIF is
not set, should you always call the ath_start_rx_poll method
even if ani is disabled in the ath9k_bss_iter method since
the PRIM_STA_VIF flag is set earlier in that code)?
static int ath9k_add_interface(struct ieee80211_hw *hw,
struct ieee80211_vif *vif)
@@ -1948,6 +2086,8 @@ static void ath9k_bss_iter(void *data, u8 *mac, struct ieee80211_vif *vif)
if (!common->disable_ani) {
sc->sc_flags |= SC_OP_ANI_RUN;
ath_start_ani(common);
+ sc->rx.stop_rx_poll = false;
+ ath_start_rx_poll(sc, 300);
}
}
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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