wcn36xx: ensure pairing of init_scan/finish_scan and start_scan/end_scan

BugLink: https://bugs.launchpad.net/bugs/1959376
[ Upstream commit 8f1ba8b0ee2679f0b3d22d2a5c1bc70c436fd872 ]

An SMD capture from the downstream prima driver on WCN3680B shows the
following command sequence for connected scans:

- init_scan_req
    - start_scan_req, channel 1
    - end_scan_req, channel 1
    - start_scan_req, channel 2
    - ...
    - end_scan_req, channel 3
- finish_scan_req
- init_scan_req
    - start_scan_req, channel 4
    - ...
    - end_scan_req, channel 6
- finish_scan_req
- ...
    - end_scan_req, channel 165
- finish_scan_req

Upstream currently never calls wcn36xx_smd_end_scan, and in some cases[1]
still sends finish_scan_req twice in a row or before init_scan_req. A
typical connected scan looks like this:

- init_scan_req
    - start_scan_req, channel 1
- finish_scan_req
- init_scan_req
    - start_scan_req, channel 2
- ...
    - start_scan_req, channel 165
- finish_scan_req
- finish_scan_req

This patch cleans up scanning so that init/finish and start/end are always
paired together and correctly nested.

- init_scan_req
    - start_scan_req, channel 1
    - end_scan_req, channel 1
- finish_scan_req
- init_scan_req
    - start_scan_req, channel 2
    - end_scan_req, channel 2
- ...
    - start_scan_req, channel 165
    - end_scan_req, channel 165
- finish_scan_req

Note that upstream will not do batching of 3 active-probe scans before
returning to the operating channel, and this patch does not change that.
To match downstream in this aspect, adjust IEEE80211_PROBE_DELAY and/or
the 125ms max off-channel time in ieee80211_scan_state_decision.

[1]: commit d195d7aac09b ("wcn36xx: Ensure finish scan is not requested
before start scan") addressed one case of finish_scan_req being sent
without a preceding init_scan_req (the case of the operating channel
coinciding with the first scan channel); two other cases are:
1) if SW scan is started and aborted immediately, without scanning any
   channels, we send a finish_scan_req without ever sending init_scan_req,
   and
2) as SW scan logic always returns us to the operating channel before
   calling wcn36xx_sw_scan_complete, finish_scan_req is always sent twice
   at the end of a SW scan

Fixes: 8e84c2582169 ("wcn36xx: mac80211 driver for Qualcomm WCN3660/WCN3680 hardware")
Signed-off-by: Benjamin Li <benl@squareup.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211027170306.555535-4-benl@squareup.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/net/wireless/ath/wcn36xx/main.c b/drivers/net/wireless/ath/wcn36xx/main.c
index 5d82aca370a7275508f0aa2a072b8251e546cbe5..cf9e1396bd046224ae34ab0eede07477c6601c74 100644 (file)
--- a/drivers/net/wireless/ath/wcn36xx/main.c
+++ b/drivers/net/wireless/ath/wcn36xx/main.c
@@ -400,6 +400,7 @@ static void wcn36xx_change_opchannel(struct wcn36xx *wcn, int ch)
 static int wcn36xx_config(struct ieee80211_hw *hw, u32 changed)
 {
        struct wcn36xx *wcn = hw->priv;
+       int ret;
 
        wcn36xx_dbg(WCN36XX_DBG_MAC, "mac config changed 0x%08x\n", changed);
 
@@ -415,17 +416,31 @@ static int wcn36xx_config(struct ieee80211_hw *hw, u32 changed)
                         * want to receive/transmit regular data packets, then
                         * simply stop the scan session and exit PS mode.
                         */
-                       wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN,
-                                               wcn->sw_scan_vif);
-                       wcn->sw_scan_channel = 0;
+                       if (wcn->sw_scan_channel)
+                               wcn36xx_smd_end_scan(wcn, wcn->sw_scan_channel);
+                       if (wcn->sw_scan_init) {
+                               wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN,
+                                                       wcn->sw_scan_vif);
+                       }
                } else if (wcn->sw_scan) {
                        /* A scan is ongoing, do not change the operating
                         * channel, but start a scan session on the channel.
                         */
-                       wcn36xx_smd_init_scan(wcn, HAL_SYS_MODE_SCAN,
-                                             wcn->sw_scan_vif);
+                       if (wcn->sw_scan_channel)
+                               wcn36xx_smd_end_scan(wcn, wcn->sw_scan_channel);
+                       if (!wcn->sw_scan_init) {
+                               /* This can fail if we are unable to notify the
+                                * operating channel.
+                                */
+                               ret = wcn36xx_smd_init_scan(wcn,
+                                                           HAL_SYS_MODE_SCAN,
+                                                           wcn->sw_scan_vif);
+                               if (ret) {
+                                       mutex_unlock(&wcn->conf_mutex);
+                                       return -EIO;
+                               }
+                       }
                        wcn36xx_smd_start_scan(wcn, ch);
-                       wcn->sw_scan_channel = ch;
                } else {
                        wcn36xx_change_opchannel(wcn, ch);
                }
@@ -713,7 +728,12 @@ static void wcn36xx_sw_scan_complete(struct ieee80211_hw *hw,
        struct wcn36xx *wcn = hw->priv;
 
        /* ensure that any scan session is finished */
-       wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN, wcn->sw_scan_vif);
+       if (wcn->sw_scan_channel)
+               wcn36xx_smd_end_scan(wcn, wcn->sw_scan_channel);
+       if (wcn->sw_scan_init) {
+               wcn36xx_smd_finish_scan(wcn, HAL_SYS_MODE_SCAN,
+                                       wcn->sw_scan_vif);
+       }
        wcn->sw_scan = false;
        wcn->sw_scan_opchannel = 0;
 }

diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
index 70bffe3d87a123b6755e84b841d7225d7e60c3a4..6ac770d8271eb2b3215c5e87a4204ce9c9b71481 100644 (file)
--- a/drivers/net/wireless/ath/wcn36xx/smd.c
+++ b/drivers/net/wireless/ath/wcn36xx/smd.c
@@ -721,6 +721,7 @@ int wcn36xx_smd_init_scan(struct wcn36xx *wcn, enum wcn36xx_hal_sys_mode mode,
                wcn36xx_err("hal_init_scan response failed err=%d\n", ret);
                goto out;
        }
+       wcn->sw_scan_init = true;
 out:
        mutex_unlock(&wcn->hal_mutex);
        return ret;
@@ -751,6 +752,7 @@ int wcn36xx_smd_start_scan(struct wcn36xx *wcn, u8 scan_channel)
                wcn36xx_err("hal_start_scan response failed err=%d\n", ret);
                goto out;
        }
+       wcn->sw_scan_channel = scan_channel;
 out:
        mutex_unlock(&wcn->hal_mutex);
        return ret;
@@ -781,6 +783,7 @@ int wcn36xx_smd_end_scan(struct wcn36xx *wcn, u8 scan_channel)
                wcn36xx_err("hal_end_scan response failed err=%d\n", ret);
                goto out;
        }
+       wcn->sw_scan_channel = 0;
 out:
        mutex_unlock(&wcn->hal_mutex);
        return ret;
@@ -822,6 +825,7 @@ int wcn36xx_smd_finish_scan(struct wcn36xx *wcn,
                wcn36xx_err("hal_finish_scan response failed err=%d\n", ret);
                goto out;
        }
+       wcn->sw_scan_init = false;
 out:
        mutex_unlock(&wcn->hal_mutex);
        return ret;

diff --git a/drivers/net/wireless/ath/wcn36xx/wcn36xx.h b/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
index e9560f35e9bcfa6d400464580631b84e3e3e73c1..428546a6047f0457d124137bf2c288754724afb0 100644 (file)
--- a/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
+++ b/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
@@ -246,6 +246,7 @@ struct wcn36xx {
        struct cfg80211_scan_request *scan_req;
        bool                    sw_scan;
        u8                      sw_scan_opchannel;
+       bool                    sw_scan_init;
        u8                      sw_scan_channel;
        struct ieee80211_vif    *sw_scan_vif;
        struct mutex            scan_lock;