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Message-ID: <9a933103-afbc-3278-3d2e-ade77b0e4b09@linaro.org>
Date: Wed, 27 Oct 2021 23:30:18 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Benjamin Li <benl@...areup.com>, Kalle Valo <kvalo@...eaurora.org>
Cc: Joseph Gates <jgates@...areup.com>,
Loic Poulain <loic.poulain@...aro.org>,
linux-arm-msm@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Eugene Krasnikov <k.eugene.e@...il.com>,
"John W. Linville" <linville@...driver.com>,
wcn36xx@...ts.infradead.org, linux-wireless@...r.kernel.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] wcn36xx: ensure pairing of init_scan/finish_scan
and start_scan/end_scan
On 27/10/2021 18:03, Benjamin Li wrote:
> 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@...areup.com>
> ---
> drivers/net/wireless/ath/wcn36xx/main.c | 34 +++++++++++++++++-----
> drivers/net/wireless/ath/wcn36xx/smd.c | 4 +++
> drivers/net/wireless/ath/wcn36xx/wcn36xx.h | 1 +
> 3 files changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/wcn36xx/main.c b/drivers/net/wireless/ath/wcn36xx/main.c
> index 18383d0fc0933..37b4016f020c9 100644
> --- 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);
> }
> @@ -723,7 +738,12 @@ 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;
> }
> diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
> index 3cecc8f9c9647..830341be72673 100644
> --- 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 1c8d918137da2..fbd0558c2c196 100644
> --- a/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
> +++ b/drivers/net/wireless/ath/wcn36xx/wcn36xx.h
> @@ -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;
>
LGTM
Tested-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
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