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Adrian Chadd 0ffc652e9e [ath] fix target beacon interval programming for STA mode when in powersave.
This bug has been bugging me for quite some time.  I finally sat down
with enough coffee to figure it out.

The short of it - rounding up to the next intval multiple of the TSF value
only works if the AP is transmitting all its beacons on an interval of
the TSF.  If it isn't - for example, doing staggered beacons on a multi-VAP
setup with a single hardware TSF - then weird things occur.

The long of it -

When powersave is enabled, the MAC and PHY are partially powered off.
They can't receive any packets (or transmit, for that matter.)
The target beacon timer programming will wake up the MAC/PHY just before
the beacon is supposed to be received (well, strictly speaking, at DTIM
so it can see the TIM - traffic information map - telling the STA whether
any traffic is there for it) and it happens automatically.

However, this relies on the target beacon time being programmed correctly.
If it isn't then the hardware will wake up and not hear any beacons -
and then it'll be asleep for said beacons.  After enough of this, net80211
will give up and assume the AP went away.

This should fix both TSFOOR interrupts and disconnects from APs with powersave
enabled.

The annoying bit is that it only happens if APs stagger things or start
on a non-zero TSF.  So, this would sometimes be fine and sometimes not be
fine.

What:

* I don't know (yet) why the code rounds up to the next intval.
  For now, just disable rounding it and trust the value we get.

TODO:

* If we do see a beacon miss in STA mode then we should transition
  out of sleep for a while so we can hear beacons to resync against.
  I'd love a patch from someone to enable that particular behaviour.
  Note - that doesn't require that net80211 brings the chip out of
  sleep state - only that we wake the chip up through to full-on and
  then let it go to sleep again when we've seen a beacon.  The wifi
  stack and AP can still completely just stay believing we're in sleep
  mode.

Tested:

* AR9485, STA mode, powersave enabled

MFC after:	1 week
Relnotes:	Yes
2016-11-28 02:59:33 +00:00
bin [dd] Revert the capsicum bits for now until it gets fixed. 2016-11-19 18:19:21 +00:00
cddl MFV r308989: 6428 set canmount=off on unmounted filesystem tries to 2016-11-24 10:11:09 +00:00
contrib Pull in r283060 from upstream llvm trunk (by Hal Finkel): 2016-11-25 18:12:13 +00:00
crypto MFV r308196: 2016-11-02 06:49:25 +00:00
etc Merge ^/head r308870 through r309105. 2016-11-24 14:39:04 +00:00
gnu Add WITH_LLD_AS_LD build knob 2016-11-25 13:15:28 +00:00
include hyperv/vss: Add driver and tools for VSS 2016-11-15 02:36:12 +00:00
kerberos5 DIRDEPS_BUILD: Update dependencies 2016-06-14 16:55:05 +00:00
lib Launder VPO_NOSYNC pages upon vnode deactivation. 2016-11-26 21:00:27 +00:00
libexec Fix _mips_rtld_bind() to handle ELF filters. 2016-11-23 20:21:53 +00:00
release Sync the rtwn(4) entry with the manpage. 2016-11-24 10:35:49 +00:00
rescue DIRDEPS_BUILD: Update dependencies. 2016-11-13 00:11:30 +00:00
sbin Allocate a struct ifreq rather than using a (wrong) computed size for 2016-11-22 22:45:15 +00:00
secure Prefer ACFLAGS over CFLAGS for compiling aarch64 assembly files. 2016-10-26 20:12:30 +00:00
share The function vm_page_cache() no longer exists. Remove its man page. 2016-11-27 01:44:31 +00:00
sys [ath] fix target beacon interval programming for STA mode when in powersave. 2016-11-28 02:59:33 +00:00
targets Merge ^/head r308491 through r308841. 2016-11-19 16:05:55 +00:00
tests Add test case for >65535 segment coredumps 2016-11-01 19:18:16 +00:00
tools Add a few missed clang 3.9.0 files to OptionalObsoleteFiles. 2016-11-27 14:19:19 +00:00
usr.bin indent(1): Properly handle the wide string literal and wide char constant L. 2016-11-27 20:38:14 +00:00
usr.sbin Properly initialize nextp 2016-11-27 19:27:13 +00:00
.arcconfig callsign isn't required anymore 2016-09-29 06:19:45 +00:00
.arclint
COPYRIGHT Bump copyright year. 2015-12-31 11:21:45 +00:00
LOCKS
MAINTAINERS Remove myself from kern_timeout.c yeah! 2016-07-27 20:37:32 +00:00
Makefile Add full softfloat and hardfloat support for RISC-V. 2016-11-16 15:21:32 +00:00
Makefile.inc1 Add WITH_LLD_AS_LD build knob 2016-11-25 13:15:28 +00:00
Makefile.libcompat Fix in-tree GCC builds after r304681. 2016-08-23 19:29:37 +00:00
ObsoleteFiles.inc The function vm_page_cache() no longer exists. Remove its man page. 2016-11-27 01:44:31 +00:00
README README: remove nonexistent 'games' directory. 2016-05-18 10:43:13 +00:00
UPDATING Add UPDATING entry for clang/llvm 3.9.0 import. 2016-11-24 22:18:55 +00:00

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