[ath9k-devel] [PATCH] ath9k: Fix softlockup in AR9485

[Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>]

Hi John,

On Wednesday 13 June 2012 01:14 AM, John W. Linville wrote:
> Do you have a version that applies to 3.5 and earlier?

thanks, will soon send a back ported version for 3.5. thanks.

>
> On Tue, Jun 12, 2012 at 08:13:43PM +0530, Mohammed Shafi Shajakhan wrote:
>> From: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com>
>>
>> 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=811142
>>
>> Reported-by: Rolf Offermanns<rolf.offermanns@gmx.net>
>> Cc: stable at vger.kernel.org
>> Tested-by: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com>
>> Signed-off-by: Mohammed Shafi Shajakhan<mohammed@qca.qualcomm.com>
>> ---
>>   drivers/net/wireless/ath/ath9k/link.c |    8 ++++++++
>>   1 files changed, 8 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/link.c b/drivers/net/wireless/ath/ath9k/link.c
>> index 0cc4c70..a105c94 100644
>> --- a/drivers/net/wireless/ath/ath9k/link.c
>> +++ b/drivers/net/wireless/ath/ath9k/link.c
>> @@ -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);
>> --
>> 1.7.0.4
>>
>>
>


-- 
thanks,
shafi