diff mbox series

mac80211: Enable power save after receiving NULL packet ACK

Message ID 20210227055815.14838-1-bassem@morsemicro.com
State Under Review
Delegated to: Johannes Berg
Headers show
Series mac80211: Enable power save after receiving NULL packet ACK | expand

Commit Message

Bassem Dawood Feb. 27, 2021, 5:58 a.m. UTC
Trigger dynamic_ps_timer to re-evaluate power saving once a null function
packet (with PM = 1) is ACKed.

Signed-off-by: Bassem Dawood <bassem@morsemicro.com>
---
 net/mac80211/status.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Johannes Berg April 8, 2021, 1:26 p.m. UTC | #1
On Sat, 2021-02-27 at 16:58 +1100, Bassem Dawood wrote:
> Trigger dynamic_ps_timer to re-evaluate power saving once a null function
> packet (with PM = 1) is ACKed.

Can you please say what this fixes/why the change is needed?

johannes
Bassem Dawood April 9, 2021, 1:32 a.m. UTC | #2
On Thu, Apr 08, 2021 at 03:26:06PM +0200, Johannes Berg wrote:
> On Sat, 2021-02-27 at 16:58 +1100, Bassem Dawood wrote:
> > Trigger dynamic_ps_timer to re-evaluate power saving once a null function
> > packet (with PM = 1) is ACKed.
> 
> Can you please say what this fixes/why the change is needed?
> 
> johannes
> 

Sure.

For drivers that declare PS_NULLFUNC_STACK, when sleeping, mac80211 would send a nullfunc (with PS bit set). It won't notify the driver yet (waiting for the NULLFUNC ACK).


a/net/mac80211/mlme.c: void ieee80211_dynamic_ps_enable_work(struct work_struct *work) 

	if (ieee80211_hw_check(&local->hw, PS_NULLFUNC_STACK) &&
	    !(ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
		if (drv_tx_frames_pending(local)) {
			mod_timer(&local->dynamic_ps_timer, jiffies +
				  msecs_to_jiffies(
				  local->hw.conf.dynamic_ps_timeout));
		} else {
			ieee80211_send_nullfunc(local, sdata, true);
			/* Flush to get the tx status of nullfunc frame */
			ieee80211_flush_queues(local, sdata, false);
		}
	}

	if (!(ieee80211_hw_check(&local->hw, REPORTS_TX_ACK_STATUS) &&
	      ieee80211_hw_check(&local->hw, PS_NULLFUNC_STACK)) ||
	    (ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
		ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
		local->hw.conf.flags |= IEEE80211_CONF_PS;
		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
	}

On reception of the ACK, mac80211 will set the  IEEE80211_STA_NULLFUNC_ACKED flag, but won't re-evaluate dynamic_ps_enable_work. So drivers won't get notified to sleep (until ieee80211_dynamic_ps_enable_work is re-evaluated through any other path).

a/net/mac80211/status.c:static void __ieee80211_tx_status(struct ieee80211_hw *hw,
				  struct ieee80211_tx_status *status,
				  int rates_idx, int retry_count) 

	if (ieee80211_is_any_nullfunc(fc) &&
	    ieee80211_has_pm(fc) &&
	    ieee80211_hw_check(&local->hw, REPORTS_TX_ACK_STATUS) &&
	    !(info->flags & IEEE80211_TX_CTL_INJECTED) &&
	    local->ps_sdata && !(local->scanning)) {
		if (info->flags & IEEE80211_TX_STAT_ACK) {
			local->ps_sdata->u.mgd.flags |=
					IEEE80211_STA_NULLFUNC_ACKED;
		} else
			mod_timer(&local->dynamic_ps_timer, jiffies +
					msecs_to_jiffies(10));
	}

This change makes sure  ieee80211_dynamic_ps_enable_work is evaluated once a NULLFUNC is ACKED for a more conssitent notification of the driver.

Regards,
Bassem
Bassem Dawood April 20, 2021, 4:58 a.m. UTC | #3
On Fri, Apr 09, 2021 at 11:32:19AM +1000, Bassem Fahmy wrote:
> On Thu, Apr 08, 2021 at 03:26:06PM +0200, Johannes Berg wrote:
> > On Sat, 2021-02-27 at 16:58 +1100, Bassem Dawood wrote:
> > > Trigger dynamic_ps_timer to re-evaluate power saving once a null function
> > > packet (with PM = 1) is ACKed.
> > 
> > Can you please say what this fixes/why the change is needed?
> > 
> > johannes
> > 
> 
> Sure.
> 
> For drivers that declare PS_NULLFUNC_STACK, when sleeping, mac80211 would send a nullfunc (with PS bit set). It won't notify the driver yet (waiting for the NULLFUNC ACK).
> 
> 
> a/net/mac80211/mlme.c: void ieee80211_dynamic_ps_enable_work(struct work_struct *work) 
> 
> 	if (ieee80211_hw_check(&local->hw, PS_NULLFUNC_STACK) &&
> 	    !(ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
> 		if (drv_tx_frames_pending(local)) {
> 			mod_timer(&local->dynamic_ps_timer, jiffies +
> 				  msecs_to_jiffies(
> 				  local->hw.conf.dynamic_ps_timeout));
> 		} else {
> 			ieee80211_send_nullfunc(local, sdata, true);
> 			/* Flush to get the tx status of nullfunc frame */
> 			ieee80211_flush_queues(local, sdata, false);
> 		}
> 	}
> 
> 	if (!(ieee80211_hw_check(&local->hw, REPORTS_TX_ACK_STATUS) &&
> 	      ieee80211_hw_check(&local->hw, PS_NULLFUNC_STACK)) ||
> 	    (ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
> 		ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
> 		local->hw.conf.flags |= IEEE80211_CONF_PS;
> 		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
> 	}
> 
> On reception of the ACK, mac80211 will set the  IEEE80211_STA_NULLFUNC_ACKED flag, but won't re-evaluate dynamic_ps_enable_work. So drivers won't get notified to sleep (until ieee80211_dynamic_ps_enable_work is re-evaluated through any other path).
> 
> a/net/mac80211/status.c:static void __ieee80211_tx_status(struct ieee80211_hw *hw,
> 				  struct ieee80211_tx_status *status,
> 				  int rates_idx, int retry_count) 
> 
> 	if (ieee80211_is_any_nullfunc(fc) &&
> 	    ieee80211_has_pm(fc) &&
> 	    ieee80211_hw_check(&local->hw, REPORTS_TX_ACK_STATUS) &&
> 	    !(info->flags & IEEE80211_TX_CTL_INJECTED) &&
> 	    local->ps_sdata && !(local->scanning)) {
> 		if (info->flags & IEEE80211_TX_STAT_ACK) {
> 			local->ps_sdata->u.mgd.flags |=
> 					IEEE80211_STA_NULLFUNC_ACKED;
> 		} else
> 			mod_timer(&local->dynamic_ps_timer, jiffies +
> 					msecs_to_jiffies(10));
> 	}
> 
> This change makes sure  ieee80211_dynamic_ps_enable_work is evaluated once a NULLFUNC is ACKED for a more conssitent notification of the driver.
> 
> Regards,
> Bassem

Hi Johannes,

Following up on this. Is the explaination clear or you need more description?

Regareds,
Bassem
diff mbox series

Patch

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index 3485610755ef..c106f81478df 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -1013,9 +1013,9 @@  static void __ieee80211_tx_status(struct ieee80211_hw *hw,
 		if (info->flags & IEEE80211_TX_STAT_ACK) {
 			local->ps_sdata->u.mgd.flags |=
 					IEEE80211_STA_NULLFUNC_ACKED;
-		} else
-			mod_timer(&local->dynamic_ps_timer, jiffies +
-					msecs_to_jiffies(10));
+		}
+		mod_timer(&local->dynamic_ps_timer, jiffies +
+				msecs_to_jiffies(10));
 	}
 
 	ieee80211_report_used_skb(local, skb, false);