[PATCH 2/2] wifi: mac80211: keep the tpt LED solid below an idle threshold

[Salah Ahmed]

The phy throughput LED blinks whenever the counted traffic is non-zero:
tpt_trig_timer() walks the blink table from the top and only falls back to
solid on when no entry matches, which needs tpt == 0 exactly. An access
point transmits the broadcast and multicast it bridges even with zero
associated stations - measured at roughly 2 KiB/s on a quiet LAN - so the
LED blinks at the slowest table step (334 ms) forever and stops indicating
whether anything is actually being transferred.

Count anything below 12 KiB/s (96 kbit/s) as idle instead. That is the
threshold the userspace activity monitors used on these devices were tuned
against: it is above the background of a quiet LAN and well below any real
transfer, so the LED is solid while nothing moves and still tracks the
blink table as soon as a station transfers data.

Signed-off-by: Salah Ahmed <haddad2inc@xxxxxxxxx>
---
 net/mac80211/led.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/net/mac80211/led.c b/net/mac80211/led.c
index b5600d223..78fffe122 100644
--- a/net/mac80211/led.c
+++ b/net/mac80211/led.c
@@ -9,6 +9,16 @@
 #include <linux/export.h>
 #include "led.h"
 
+/*
+ * Below this throughput the tpt LED stays solid on instead of blinking at the
+ * slowest step of the table. An access point transmits the LAN broadcast and
+ * multicast it bridges even with zero associated stations (measured ~2 KiB/s),
+ * which is enough to keep the LED blinking forever while nothing is actually
+ * transferred. 12 KiB/s (96 kbit/s) is the idle rate the userspace activity
+ * monitors this behaviour was derived from were tuned against.
+ */
+#define IEEE80211_TPT_LED_IDLE_KBIT	(12 * 8)
+
 void ieee80211_led_assoc(struct ieee80211_local *local, bool associated)
 {
 	if (!atomic_read(&local->assoc_led_active))
@@ -270,6 +280,12 @@ static void tpt_trig_timer(struct timer_list *t)
 
 	tpt = tpt_trig_traffic(local, tpt_trig);
 
+	/* Treat anything below the idle threshold as no traffic, so that the
+	 * LED is solid while the radio only carries background broadcast.
+	 */
+	if (tpt < IEEE80211_TPT_LED_IDLE_KBIT)
+		tpt = 0;
+
 	/* default to just solid on */
 	on = 1;
 	off = 0;
-- 
2.53.0