Commit 64bc1239 authored by Mohammed Shafi Shajakhan's avatar Mohammed Shafi Shajakhan Committed by John W. Linville

ath9k: Fix softlockup in AR9485

steps to recreate:
load latest ath9k driver with AR9485
stop the network-manager and wpa_supplicant
bring the interface up

	Call Trace:
	[<ffffffffa0517490>] ? ath_hw_check+0xe0/0xe0 [ath9k]
	[<ffffffff812cd1e8>] __const_udelay+0x28/0x30
	[<ffffffffa03bae7a>] ar9003_get_pll_sqsum_dvc+0x4a/0x80 [ath9k_hw]
	[<ffffffffa05174eb>] ath_hw_pll_work+0x5b/0xe0 [ath9k]
	[<ffffffff810744fe>] process_one_work+0x11e/0x470
	[<ffffffff8107530f>] worker_thread+0x15f/0x360
	[<ffffffff810751b0>] ? manage_workers+0x230/0x230
	[<ffffffff81079af3>] kthread+0x93/0xa0
	[<ffffffff815fd3a4>] kernel_thread_helper+0x4/0x10
	[<ffffffff81079a60>] ? kthread_freezable_should_stop+0x70/0x70
	[<ffffffff815fd3a0>] ? gs_change+0x13/0x13

ensure that the PLL-WAR for AR9485/AR9340 is executed only if the STA is
associated (or) IBSS/AP mode had started beaconing. Ideally this WAR
is needed to recover from some rare beacon stuck during stress testing.
Before the STA is associated/IBSS had started beaconing, PLL4(0x1618c)
always seem to have zero even though we had configured PLL3(0x16188) to
query about PLL's locking status. When we keep on polling infinitely PLL4's
8th bit(ie check for PLL locking measurements is done), machine hangs
due to softlockup.

fixes https://bugzilla.redhat.com/show_bug.cgi?id=811142Reported-by: default avatarRolf Offermanns <rolf.offermanns@gmx.net>
Cc: stable@vger.kernel.org
Tested-by: default avatarMohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: default avatarMohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent a197b76c
......@@ -136,6 +136,14 @@ void ath_hw_pll_work(struct work_struct *work)
u32 pll_sqsum;
struct ath_softc *sc = container_of(work, struct ath_softc,
hw_pll_work.work);
/*
* ensure that the PLL WAR is executed only
* after the STA is associated (or) if the
* beaconing had started in interfaces that
* uses beacons.
*/
if (!test_bit(SC_OP_BEACONS, &sc->sc_flags))
return;
ath9k_ps_wakeup(sc);
pll_sqsum = ar9003_get_pll_sqsum_dvc(sc->sc_ah);
......
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