When QCA988X cycle counter HW register wraps around it resets to 0x7fffffff instead of 0. All other cycle counter related registers are divided by 2 so they never wraparound themselves. QCA61X4 has a uniform CC and it wraparounds in a regular fashion though.
Worst case wraparound time is approx 24 seconds (2**31 / 88MHz). Since scan channel visit times are max 5 seconds (offchannel case) it is guaranteed there's been at most 1 wraparound and it is possible to compute survey data. This fixes some occasional incorrect survey data on QCA988X as some channels (depending on how/when scan/offchannel requests were requested) would have approx 24 sec active time which wasn't actually the case. This should help make hostapd ACS more reliable. Reported-by: Srinivasa Duvvuri <[email protected]> Signed-off-by: Michal Kazior <[email protected]> --- Notes: v3: * split into 2 separate patches * don't ignore all wraparound data: scans can be computed * apply the shifted wraparound fix only for QCA988X * improve commit log drivers/net/wireless/ath/ath10k/core.c | 15 +++++++++++++++ drivers/net/wireless/ath/ath10k/core.h | 12 ++++++++++++ drivers/net/wireless/ath/ath10k/wmi.c | 14 ++++++++++++-- 3 files changed, 39 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c index bcccae19325d..0cc2122d6921 100644 --- a/drivers/net/wireless/ath/ath10k/core.c +++ b/drivers/net/wireless/ath/ath10k/core.c @@ -48,6 +48,7 @@ static const struct ath10k_hw_params ath10k_hw_params_list[] = { .name = "qca988x hw2.0", .patch_load_addr = QCA988X_HW_2_0_PATCH_LOAD_ADDR, .uart_pin = 7, + .has_shifted_cc_wraparound = true, .fw = { .dir = QCA988X_HW_2_0_FW_DIR, .fw = QCA988X_HW_2_0_FW_FILE, @@ -102,6 +103,20 @@ static const struct ath10k_hw_params ath10k_hw_params_list[] = { }, }; +void ath10k_core_get_cc_delta(struct ath10k *ar, + u32 *cc_delta, u32 *rcc_delta, + u32 cc, u32 rcc, + u32 cc_prev, u32 rcc_prev) +{ + if (ar->hw_params.has_shifted_cc_wraparound && cc < cc_prev) { + cc_prev -= 0x7fffffff; + rcc *= 2; + } + + *cc_delta = cc - cc_prev; + *rcc_delta = rcc - rcc_prev; +} + static void ath10k_send_suspend_complete(struct ath10k *ar) { ath10k_dbg(ar, ATH10K_DBG_BOOT, "boot suspend complete\n"); diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h index 827b3d79ed0c..fb403972b1c5 100644 --- a/drivers/net/wireless/ath/ath10k/core.h +++ b/drivers/net/wireless/ath/ath10k/core.h @@ -572,6 +572,13 @@ struct ath10k { u32 patch_load_addr; int uart_pin; + /* This is true if given HW chip has a quirky Cycle Counter + * wraparound which resets to 0x7fffffff instead of 0. All + * other CC related counters (e.g. Rx Clear Count) are divided + * by 2 so they never wraparound themselves. + */ + bool has_shifted_cc_wraparound; + struct ath10k_hw_params_fw { const char *dir; const char *fw; @@ -742,4 +749,9 @@ void ath10k_core_stop(struct ath10k *ar); int ath10k_core_register(struct ath10k *ar, u32 chip_id); void ath10k_core_unregister(struct ath10k *ar); +void ath10k_core_get_cc_delta(struct ath10k *ar, + u32 *cc_delta, u32 *rcc_delta, + u32 cc, u32 rcc, + u32 cc_prev, u32 rcc_prev); + #endif /* _CORE_H_ */ diff --git a/drivers/net/wireless/ath/ath10k/wmi.c b/drivers/net/wireless/ath/ath10k/wmi.c index 0fabe689179c..52ed48b7e5f9 100644 --- a/drivers/net/wireless/ath/ath10k/wmi.c +++ b/drivers/net/wireless/ath/ath10k/wmi.c @@ -1640,8 +1640,18 @@ void ath10k_wmi_event_chan_info(struct ath10k *ar, struct sk_buff *skb) * visited channel. The reported cycle count is global * and per-channel cycle count must be calculated */ - cycle_count -= ar->survey_last_cycle_count; - rx_clear_count -= ar->survey_last_rx_clear_count; + /* Worst case wraparound time is approx 24 seconds (2**31 / + * 88MHz). Since scan channel visit times are max 5 seconds + * (offchannel case) it is guaranteed there's been at most 1 + * wraparound and it is possible to compute survey data. + */ + ath10k_core_get_cc_delta(ar, + &cycle_count, + &rx_clear_count, + cycle_count, + rx_clear_count, + ar->survey_last_cycle_count, + ar->survey_last_rx_clear_count); survey = &ar->survey[idx]; survey->time = WMI_CHAN_INFO_MSEC(cycle_count); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
