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Date: Thu, 29 Feb 2024 13:41:17 -0800
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Subject: Re: [PATCH v2 11/13] wifi: mac80211: fix advertised TTLM scheduling
Content-Language: en-US
To: Miri Korenblit <miriam.rachel.korenblit@intel.com>,
 johannes@sipsolutions.net
Cc: linux-wireless@vger.kernel.org, Ayala Beker <ayala.beker@intel.com>,
 Johannes Berg <johannes.berg@intel.com>
References: <20231220133549.bdfb8a9c7c54.I973563562969a27fea8ec5685b96a3a47afe142f@changeid>
 <20231220133549.15079c34e5c8.I0dd50bcceff5953080cdd7aee5118b72c78c6507@changeid>
From: Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
In-Reply-To: <20231220133549.15079c34e5c8.I0dd50bcceff5953080cdd7aee5118b72c78c6507@changeid>
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On 12/20/23 03:41, Miri Korenblit wrote:
> From: Ayala Beker <ayala.beker@intel.com>
> 
> Handle a case of time overflow, where the switch time might
> be smaller than the partial TSF in the beacon.
> Additionally, apply advertised TTLM earlier in order to be
> ready on time on the newly activated links.
> 
> Fixes: 702e80470a33 ("wifi: mac80211: support handling of advertised TID-to-link mapping")
> Signed-off-by: Ayala Beker <ayala.beker@intel.com>
> Reviewed-by: Johannes Berg <johannes.berg@intel.com>
> Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>

While rebasing my 6.7 tree on 6.8, I notice this patch applied, which I think means
it was not applied to 6.8 upstream.  Was that on purpose?

Thanks,
Ben

> ---
> v2: Fix wrong email addresses
> ---
>   net/mac80211/mlme.c | 49 ++++++++++++++++++++++++++++++++++++---------
>   1 file changed, 40 insertions(+), 9 deletions(-)
> 
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index fe0be3e5731b..b526ce589d4d 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -43,6 +43,9 @@
>   #define IEEE80211_ASSOC_TIMEOUT_SHORT	(HZ / 10)
>   #define IEEE80211_ASSOC_MAX_TRIES	3
>   
> +#define IEEE80211_ADV_TTLM_SAFETY_BUFFER_MS msecs_to_jiffies(100)
> +#define IEEE80211_ADV_TTLM_ST_UNDERFLOW 0xff00
> +
>   static int max_nullfunc_tries = 2;
>   module_param(max_nullfunc_tries, int, 0644);
>   MODULE_PARM_DESC(max_nullfunc_tries,
> @@ -5965,6 +5968,13 @@ ieee80211_parse_adv_t2l(struct ieee80211_sub_if_data *sdata,
>   	pos++;
>   
>   	ttlm_info->switch_time = get_unaligned_le16(pos);
> +
> +	/* Since ttlm_info->switch_time == 0 means no switch time, bump it
> +	 * by 1.
> +	 */
> +	if (!ttlm_info->switch_time)
> +		ttlm_info->switch_time = 1;
> +
>   	pos += 2;
>   
>   	if (control & IEEE80211_TTLM_CONTROL_EXPECTED_DUR_PRESENT) {
> @@ -6059,25 +6069,46 @@ static void ieee80211_process_adv_ttlm(struct ieee80211_sub_if_data *sdata,
>   		}
>   
>   		if (ttlm_info.switch_time) {
> -			u32 st_us, delay = 0;
> -			u32 ts_l26 = beacon_ts & GENMASK(25, 0);
> +			u16 beacon_ts_tu, st_tu, delay;
> +			u32 delay_jiffies;
> +			u64 mask;
>   
>   			/* The t2l map switch time is indicated with a partial
> -			 * TSF value, convert it to TSF and calc the delay
> -			 * to the start time.
> +			 * TSF value (bits 10 to 25), get the partial beacon TS
> +			 * as well, and calc the delay to the start time.
> +			 */
> +			mask = GENMASK_ULL(25, 10);
> +			beacon_ts_tu = (beacon_ts & mask) >> 10;
> +			st_tu = ttlm_info.switch_time;
> +			delay = st_tu - beacon_ts_tu;
> +
> +			/*
> +			 * If the switch time is far in the future, then it
> +			 * could also be the previous switch still being
> +			 * announced.
> +			 * We can simply ignore it for now, if it is a future
> +			 * switch the AP will continue to announce it anyway.
> +			 */
> +			if (delay > IEEE80211_ADV_TTLM_ST_UNDERFLOW)
> +				return;
> +
> +			delay_jiffies = TU_TO_JIFFIES(delay);
> +
> +			/* Link switching can take time, so schedule it
> +			 * 100ms before to be ready on time
>   			 */
> -			st_us = ieee80211_tu_to_usec(ttlm_info.switch_time);
> -			if (st_us > ts_l26)
> -				delay = st_us - ts_l26;
> +			if (delay_jiffies > IEEE80211_ADV_TTLM_SAFETY_BUFFER_MS)
> +				delay_jiffies -=
> +					IEEE80211_ADV_TTLM_SAFETY_BUFFER_MS;
>   			else
> -				continue;
> +				delay_jiffies = 0;
>   
>   			sdata->u.mgd.ttlm_info = ttlm_info;
>   			wiphy_delayed_work_cancel(sdata->local->hw.wiphy,
>   						  &sdata->u.mgd.ttlm_work);
>   			wiphy_delayed_work_queue(sdata->local->hw.wiphy,
>   						 &sdata->u.mgd.ttlm_work,
> -						 usecs_to_jiffies(delay));
> +						 delay_jiffies);
>   			return;
>   		}
>   	}

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com