Commit 8f1ba8b0 authored by Benjamin Li's avatar Benjamin Li Committed by Kalle Valo
Browse files

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



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 d195d7aa ("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: 8e84c258 ("wcn36xx: mac80211 driver for Qualcomm WCN3660/WCN3680 hardware")
Signed-off-by: default avatarBenjamin Li <benl@squareup.com>
Tested-by: default avatarBryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: default avatarKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211027170306.555535-4-benl@squareup.com
parent f02e1cc2

drivers/net/wireless/ath/wcn36xx/main.c

+27 −7
Original line number Diff line number Diff line
@@ -402,6 +402,7 @@ 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);
@@ -417,17 +418,31 @@ 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.

			 */

			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_channel = 0;

			}

		} 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,

			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);

		}
@@ -726,7 +741,12 @@ static void wcn36xx_sw_scan_complete(struct ieee80211_hw *hw, 
	wcn36xx_dbg(WCN36XX_DBG_MAC, "sw_scan_complete");



	/* 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;

}

drivers/net/wireless/ath/wcn36xx/smd.c

+4 −0
Original line number Diff line number Diff line
@@ -722,6 +722,7 @@ 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;
@@ -752,6 +753,7 @@ 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;
@@ -782,6 +784,7 @@ 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;
@@ -823,6 +826,7 @@ 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;

drivers/net/wireless/ath/wcn36xx/wcn36xx.h

+1 −0
Original line number Diff line number Diff line
@@ -248,6 +248,7 @@ 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;