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References: <20201031022311.1677337-1-bryan.odonoghue@linaro.org> <20201031022311.1677337-3-bryan.odonoghue@linaro.org>
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From:   Loic Poulain <loic.poulain@linaro.org>
Date:   Sat, 31 Oct 2020 10:57:15 +0100
Message-ID: <CAMZdPi8+_17YSOK3G+MX3dFb0vejeikBYarRR6EckysZD4G70A@mail.gmail.com>
Subject: Re: [PATCH 2/3] wcn36xx: Enable firmware link monitoring
To:     "Bryan O'Donoghue" <bryan.odonoghue@linaro.org>
Cc:     Kalle Valo <kvalo@codeaurora.org>, wcn36xx@lists.infradead.org,
        linux-wireless@vger.kernel.org, Shawn Guo <shawn.guo@linaro.org>
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On Sat, 31 Oct 2020 at 03:22, Bryan O'Donoghue
<bryan.odonoghue@linaro.org> wrote:
>
> This patch switches on CONNECTION_MONITOR. Once done it is up to the
> firmware to send keep alive and to monitor the link state.
>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> ---
>  drivers/net/wireless/ath/wcn36xx/main.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/wireless/ath/wcn36xx/main.c b/drivers/net/wireless/ath/wcn36xx/main.c
> index 706728fba72d..e924cc4acde0 100644
> --- a/drivers/net/wireless/ath/wcn36xx/main.c
> +++ b/drivers/net/wireless/ath/wcn36xx/main.c
> @@ -1246,6 +1246,7 @@ static int wcn36xx_init_ieee80211(struct wcn36xx *wcn)
>         ieee80211_hw_set(wcn->hw, HAS_RATE_CONTROL);
>         ieee80211_hw_set(wcn->hw, SINGLE_SCAN_ON_ALL_BANDS);
>         ieee80211_hw_set(wcn->hw, REPORTS_TX_ACK_STATUS);
> +       ieee80211_hw_set(wcn->hw, CONNECTION_MONITOR);

The problem could be that when connection monitor is enabled, mac80211
stop sending regular null/probe packet to the AP (as expected), but
also stop monitoring beacon miss:
https://elixir.bootlin.com/linux/v5.10-rc1/source/net/mac80211/mlme.c#L115

That's not a big problem, but that would mean that in active mode
(power_save disabled, non PS), the mac80211 will not detect if the AP
has left immediately, and in worst case, only after 30 seconds. Note
that in PS mode, beacon monitoring is well done by the firmware.

>
>         wcn->hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION) |
>                 BIT(NL80211_IFTYPE_AP) |
> --
> 2.28.0
>