RE: ATH9 driver issues on ARM64

From: Bharat Kumar Gogada
Date: Thu Dec 22 2016 - 02:19:42 EST

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Hi All,

After further debugging we know the place it hangs.

In function:
static int ath_reset_internal (struct ath_softc *sc, struct ath9k_channel *hchan)
{
disable_irq(sc->irq);
tasklet_disable(&sc->intr_tq);
tasklet_disable(&sc->bcon_tasklet);
spin_lock_bh(&sc->sc_pcu_lock);
....
....
....
if (!ath_complete_reset(sc, true)) -> This function enables hardware interrupts
r = -EIO;

out:
enable_irq(sc->irq); -> Here IRQ line state is changed to enable state
spin_unlock_bh(&sc->sc_pcu_lock);
tasklet_enable(&sc->bcon_tasklet);
tasklet_enable(&sc->intr_tq);

}

static bool ath_complete_reset(struct ath_softc *sc, bool start)
{
struct ath_hw *ah = sc->sc_ah;
struct ath_common *common = ath9k_hw_common(ah);
unsigned long flags;

ath9k_calculate_summary_state(sc, sc->cur_chan);
ath_startrecv(sc);
....
....

sc->gtt_cnt = 0;

ath9k_hw_set_interrupts(ah); -> Here hardware interrupts are being enabled
ath9k_hw_enable_interrupts(ah); -> We see hang after this line
ieee80211_wake_queues(sc->hw);
ath9k_p2p_ps_timer(sc);

return true;
}

Before changing IRQ line to to enabled state, hardware interrupts are being enabled.
Wont this cause a race condition where within this period of hardware raises an interrupt, but IRQ line state is disabled state, this will
reach the following condition making EP handler not being invoked.

void handle_simple_irq(struct irq_desc *desc)
{
raw_spin_lock(&desc->lock);
...
if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) { // This condition is reaching and becoming true.
desc->istate |= IRQS_PENDING;
goto out_unlock;
}

kstat_incr_irqs_this_cpu(desc);
handle_irq_event(desc);

out_unlock:
raw_spin_unlock(&desc->lock);
}

We see hang at that statement, without reaching back enable_irq, looks like by this time CPU is in stall.

Can any tell why hardware interrupts are being enabled before kernel changing IRQ line state?

Regards,
Bharat

>
> > On Sat, Dec 10, 2016 at 02:40:48PM +0000, Bharat Kumar Gogada wrote:
> > > Hi,
> > >
> > > After taking some more lecroy traces, we see that after 2nd ASSERT
> > > from EP
> > on ARM64 we see continuous data movement of 32 dwords or 12 dwords and
> > never sign of DEASSERT.
> > > Comparatively on working traces (x86) after 2nd assert there are
> > > only BAR
> > register reads and writes and then DEASSERT, for almost most of the
> > interrupts and we haven't seen 12 or 32 dwords data movement on this trace.
> > >
> > > I did not work on EP wifi/network drivers, any help why EP needs
> > > those many
> > number of data at scan time ?
> >
> > The device doesn't know whether it's in an x86 or an arm64 system. If
> > it works differently, it must be because the PCI core or the driver is
> > programming the device differently.
> >
> > You should be able to match up Memory transactions from the host in
> > the trace with things the driver does. For example, if you see an
> > Assert_INTx message from the device, you should eventually see a
> > Memory Read from the host to get the ISR, i.e., some read done in the bowels
> of ath9k_hw_getisr().
> >
> > I don't know how the ath9k device works, but there must be some Memory
> > Read or Write done by the driver that tells the device "we've handled this
> interrupt".
> > The device should then send a Deassert_INTx; of course, if the device
> > still requires service, e.g., because it has received more packets, it
> > might leave the INTx asserted.
> >
> > I doubt you'd see exactly the same traces on x86 and arm64 because
> > they aren't seeing the same network packets and the driver is executing at
> different rates.
> > But you should at least be able to identify interrupt assertion and
> > the actions of the driver's interrupt service routine.
>
>
> Thanks Bjorn.
>
> As you mentioned we did try to debug in that path. After we start scan after 2nd
> ASSERT we see lots of 32 and 12 dword data, and in function void
> ath9k_hw_enable_interrupts(struct ath_hw *ah) {
> ...
> ..
> REG_WRITE(ah, AR_IER, AR_IER_ENABLE);
> // EP driver hangs at this
> position after 2nd ASSERT
> // The following writes are not
> happening
> if (!AR_SREV_9100(ah)) {
> REG_WRITE(ah, AR_INTR_ASYNC_ENABLE, async_mask);
> REG_WRITE(ah, AR_INTR_ASYNC_MASK, async_mask);
>
> REG_WRITE(ah, AR_INTR_SYNC_ENABLE, sync_default);
> REG_WRITE(ah, AR_INTR_SYNC_MASK, sync_default);
> }
> ath_dbg(common, INTERRUPT, "AR_IMR 0x%x IER 0x%x\n",
> REG_READ(ah, AR_IMR), REG_READ(ah, AR_IER)); } The above funtion
> is invoked from tasklet.
> I tried several boots every it stops here. The condition (!AR_SREV_9100(ah)) is
> true as per before 1st ASSERT handling.
>
> Regards,
> Bharat
>
> >
> > > > Hello there,
> > > >
> > > > as this is a thread about ath9k and ARM64, i'm not sure if i
> > > > should answer here or not, but i have similar "stalls" with ath9k
> > > > on x86_64 (starting with 4.9rc), stack trace is posted down below
> > > > where the original
> > ARM64 stall traces are.
> > > >
> > > > Greetings,
> > > >
> > > > Tobias
> > > >
> > > >
> > > > On 08.12.2016 18:36, Kalle Valo wrote:
> > > > > Bharat Kumar Gogada <bharat.kumar.gogada@xxxxxxxxxx> writes:
> > > > >
> > > > >> > [+cc Kalle, ath9k list]
> > > > > Thanks, but please also CC linux-wireless. Full thread below for
> > > > > the folks there.
> > > > >
> > > > >>> On Thu, Dec 08, 2016 at 01:49:42PM +0000, Bharat Kumar Gogada
> > wrote:
> > > > >>>> Hi,
> > > > >>>>
> > > > >>>> Did anyone test Atheros ATH9
> > > > >>>> driver(drivers/net/wireless/ath/ath9k/)
> > > > >>>> on ARM64. The end point is TP link wifi card with which
> > > > >>>> supports only legacy interrupts.
> > > > >>> If it works on other arches and the arm64 PCI enumeration
> > > > >>> works, my first guess would be an INTx issue, e.g., maybe the
> > > > >>> driver is waiting for an interrupt that never arrives.
> > > > >> We are not sure for now.
> > > > >>>> We are trying to test it on ARM64 with
> > > > >>>> (drivers/pci/host/pcie-xilinx-nwl.c) as root port.
> > > > >>>>
> > > > >>>> EP is getting enumerated and able to link up.
> > > > >>>>
> > > > >>>> But when we start scan system gets hanged.
> > > > >>> When you say the system hangs when you start a scan, I assume
> > > > >>> you mean a wifi scan, not the PCI enumeration. A problem with
> > > > >>> a wifi scan might cause a *process* to hang, but it shouldn't
> > > > >>> hang the entire system.
> > > > >>>
> > > > >> Yes wifi scan.
> > > > >>>> When we took trace we see that after we start scan assert
> > > > >>>> message is sent but there is no de assert from end point.
> > > > >>> Are you talking about a trace from a PCIe analyzer? Do you
> > > > >>> see an Assert_INTx PCIe message on the link?
> > > > >>>
> > > > >> Yes lecroy trace, yes we do see Assert_INTx and Deassert_INTx
> > > > >> happening
> > > > when we do interface link up.
> > > > >> When we have less debug prints in Atheros driver, and do wifi
> > > > >> scan we see Assert_INTx but never Deassert_INTx,
> > > > >>>> What might cause end point not sending de assert ?
> > > > >>> If the endpoint doesn't send a Deassert_INTx message, I expect
> > > > >>> that would mean the driver didn't service the interrupt and
> > > > >>> remove the condition that caused the device to assert the
> > > > >>> interrupt in the first place.
> > > > >>>
> > > > >>> If the driver didn't receive the interrupt, it couldn't
> > > > >>> service it, of course. You could add a printk in the ath9k
> > > > >>> interrupt service routine to see if you ever get there.
> > > > >>>
> > > > >> The interrupt behavior is changing w.r.t amount of debug prints
> > > > >> we add. (I kept many prints to aid debug)
> > > > >> root@Xilinx-ZCU102-2016_3:~# iw dev
> > > > wlan0 scan
> > > > >> [ 83.064675] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.069486] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.074257] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.078260] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.083107] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.087882] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.095450] ath9k_hw_enable_interrupts 821
> > > > >> [ 83.099557] ath9k_hw_enable_interrupts 825
> > > > >> [ 83.103721] ath9k_hw_enable_interrupts 832
> > > > >> [ 83.107887] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.112748] AR_SREV_9100 0
> > > > >> [ 83.115438] ath9k_hw_enable_interrupts 848
> > > > >> [ 83.119607] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.124389] ath9k_hw_intrpend 762
> > > > >> [ 83.127761] (AR_SREV_9340(ah) val 0
> > > > >> [ 83.131234] ath9k_hw_intrpend 767
> > > > >> [ 83.134628] ath_isr 603
> > > > >> [ 83.137134] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.141995] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.146771] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.150864] ath9k_hw_enable_interrupts 821
> > > > >> [ 83.154971] ath9k_hw_enable_interrupts 825
> > > > >> [ 83.159135] ath9k_hw_enable_interrupts 832
> > > > >> [ 83.163300] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.168161] AR_SREV_9100 0
> > > > >> [ 83.170852] ath9k_hw_enable_interrupts 848
> > > > >> [ 83.170855] ath9k_hw_intrpend 762
> > > > >> [ 83.178398] (AR_SREV_9340(ah) val 0
> > > > >> [ 83.181873] ath9k_hw_intrpend 767
> > > > >> [ 83.185265] ath_isr 603
> > > > >> [ 83.187773] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.192635] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.197411] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.201414] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.206258] ath9k_hw_enable_interrupts 821
> > > > >> [ 83.210368] ath9k_hw_enable_interrupts 825
> > > > >> [ 83.214531] ath9k_hw_enable_interrupts 832
> > > > >> [ 83.218698] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.223558] AR_SREV_9100 0
> > > > >> [ 83.226243] ath9k_hw_enable_interrupts 848
> > > > >> [ 83.226246] ath9k_hw_intrpend 762
> > > > >> [ 83.233794] (AR_SREV_9340(ah) val 0
> > > > >> [ 83.237268] ath9k_hw_intrpend 767
> > > > >> [ 83.240661] ath_isr 603
> > > > >> [ 83.243169] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.248030] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.252806] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.256811] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.261651] ath9k_hw_enable_interrupts 821
> > > > >> [ 83.265753] ath9k_hw_enable_interrupts 825
> > > > >> [ 83.269919] ath9k_hw_enable_interrupts 832
> > > > >> [ 83.274083] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.278945] AR_SREV_9100 0
> > > > >> [ 83.281630] ath9k_hw_enable_interrupts 848
> > > > >> [ 83.281633] ath9k_hw_intrpend 762
> > > > >> [ 83.281634] (AR_SREV_9340(ah) val 0
> > > > >> [ 83.281637] ath9k_hw_intrpend 767
> > > > >> [ 83.281648] ath_isr 603
> > > > >> [ 83.281649] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.281651] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.281654] ath9k_hw_kill_interrupts 793
> > > > >> [ 83.312192] ath9k: ath9k_ioread32 ffffff800a400024
> > > > >> [ 83.317030] ath9k_hw_enable_interrupts 821
> > > > >> [ 83.321132] ath9k_hw_enable_interrupts 825
> > > > >> [ 83.325297] ath9k_hw_enable_interrupts 832
> > > > >> [ 83.329463] ath9k: ath9k_iowrite32 ffffff800a400024
> > > > >> [ 83.334324] AR_SREV_9100 0
> > > > >> [ 83.337014] ath9k_hw_enable_interrupts 848
> > > > >> ..
> > > > >> ..
> > > > >> This log continues until I turn off board without obtaining scanning
> result.
> > > > >>
> > > > >> In between I get following cpu stall outputs :
> > > > >> 230.457179] INFO: rcu_sched self-detected stall on CPU
> > > > >> [ 230.457185] 2-...: (31314 ticks this GP)
> > > > idle=2d1/140000000000001/0 softirq=1400/1400 fqs=36713
> > > > >> [ 230.457189] (t=36756 jiffies g=161 c=160 q=16169)
> > > > >> [ 230.457191] Task dump for CPU 2:
> > > > >> [ 230.457196] kworker/u8:4 R running task 0 1342 2
> > 0x00000002
> > > > >> [ 230.457207] Workqueue: phy0 ieee80211_scan_work [
> > > > >> 230.457208] Call trace:
> > > > >> [ 230.457214] [<ffffff8008089860>] dump_backtrace+0x0/0x198 [
> > > > >> 230.457219] [<ffffff8008089a0c>] show_stack+0x14/0x20 [
> > > > >> 230.457224] [<ffffff80080c0930>] sched_show_task+0x98/0xf8 [
> > > > >> 230.457228] [<ffffff80080c2628>] dump_cpu_task+0x40/0x50 [
> > > > >> 230.457233] [<ffffff80080e14a8>] rcu_dump_cpu_stacks+0xa0/0xf0
> > > > >> [ 230.457239] [<ffffff80080e4cd8>]
> > > > >> rcu_check_callbacks+0x468/0x748 [ 230.457243]
> > > > >> [<ffffff80080e7cfc>]
> > > > >> update_process_times+0x3c/0x68 [ 230.457249]
> > > > >> [<ffffff80080f6dfc>] tick_sched_handle.isra.5+0x3c/0x50
> > > > >> [ 230.457253] [<ffffff80080f6e54>] tick_sched_timer+0x44/0x90
> > > > >> [ 230.457257] [<ffffff80080e86b0>]
> > > > >> __hrtimer_run_queues+0xf0/0x178
> > > > >> ** 10 printk messages dropped ** [ 230.457302] f8c0:
> > > > >> 0000000000000000 0000000005f5e0ff 000000000001379a
> > > > 3866666666666620 [
> > > > >> 230.457306] f8e0: ffffff800a1b4065 0000000000000006
> > > > >> ffffff800a129000
> > > > >> ffffffc87b8010a8 [ 230.457310] f900: ffffff808a1b4057
> > > > >> ffffff800a1c3000 ffffff800a1b3000 ffffff800a13b000 [
> > > > >> 230.457314]
> > > > >> f920: 0000000000000140 0000000000000006 ffffff800a1b3b10
> > > > >> ffffff800a1c39e8 [ 230.457318] f940: 000000000000002f
> > > > >> ffffff800a1b8a98 ffffff800a1b3ae8 ffffffc87b07f990 [
> > > > >> 230.457322]
> > > > >> f960: ffffff80080d6230 ffffffc87b07f990 ffffff80080d6234
> > > > >> 0000000060000145
> > > > >> ** 1 printk messages dropped ** [ 230.457329]
> > > > >> [<ffffff8008085720>]
> > > > >> el1_irq+0xa0/0x100
> > > > >> ** 9 printk messages dropped ** [ 230.457373]
> > > > >> [<ffffff800885ad60>]
> > > > >> ieee80211_hw_config+0x50/0x290 [ 230.457377]
> > > > >> [<ffffff8008863690>]
> > > > >> ieee80211_scan_work+0x1f8/0x480 [ 230.457383]
> > > > >> [<ffffff80080b15d0>]
> > > > >> process_one_work+0x120/0x378 [ 230.457386]
> > > > >> [<ffffff80080b1870>]
> > > > >> worker_thread+0x48/0x4b0 [ 230.457391] [<ffffff80080b7108>]
> > > > >> kthread+0xd0/0xe8 [ 230.457395] [<ffffff8008085dd0>]
> > > > ret_from_fork+0x10/0x40
> > > > >> [ 230.480389] ath9k_hw_intrpend 762
> > > > >>
> > > > >>
> > > > >> [ 545.487987] ath9k: ath9k_ioread32 ffffff800a400024 [
> > > > >> 545.526189]
> > > > >> INFO: rcu_sched self-detected stall on CPU
> > > > >> [ 545.526195] 2-...: (97636 ticks this GP)
> > > > idle=2d1/140000000000001/0 softirq=1400/1400 fqs=115374
> > > > >> [ 545.526199] (t=115523 jiffies g=161 c=160 q=51066)
> > > > >> [ 545.526201] Task dump for CPU 2:
> > > > >> [ 545.526206] kworker/u8:4 R running task 0 1342 2
> > 0x00000002
> > > > >> ** 3 printk messages dropped ** [ 545.526231]
> > > > >> [<ffffff8008089a0c>]
> > > > >> show_stack+0x14/0x20
> > > > >> ** 9 printk messages dropped ** [ 545.526280]
> > > > >> [<ffffff80086a71e8>]
> > > > >> arch_timer_handler_phys+0x30/0x40 [ 545.526284]
> > > > >> [<ffffff80080dbe18>]
> > > > >> handle_percpu_devid_irq+0x78/0xa0 [ 545.526291]
> > > > >> [<ffffff80080d760c>]
> > > > >> generic_handle_irq+0x24/0x38 [ 545.526296]
> > > > >> [<ffffff80080d7944>]
> > > > >> __handle_domain_irq+0x5c/0xb8 [ 545.526299]
> > > > >> [<ffffff80080824bc>]
> > > > >> gic_handle_irq+0x64/0xc0 [ 545.526302] Exception
> > > > >> stack(0xffffffc87b07f870
> > > > to 0xffffffc87b07f990)
> > > > >> [ 545.526306] f860: 0000000000009732
> > ffffff800a1eaaa8
> > > > >> ** 8 printk messages dropped ** [ 545.526341] f980:
> > > > >> ffffff800a1c39e8
> > > > >> 0000000000000036 [ 545.526345] [<ffffff8008085720>]
> > > > >> el1_irq+0xa0/0x100 [ 545.526349] [<ffffff80080d6234>]
> > > > >> console_unlock+0x384/0x5b0 [ 545.526353] [<ffffff80080d673c>]
> > > > >> vprintk_emit+0x2dc/0x4b0 [ 545.526357] [<ffffff80080d6a50>]
> > > > >> vprintk_default+0x38/0x40 [ 545.526362] [<ffffff8008129704>]
> > > > >> printk+0x58/0x60 [ 545.526366] [<ffffff800859e3e4>]
> > > > >> ath9k_iowrite32+0x9c/0xa8 [ 545.526372] [<ffffff80085c7ca8>]
> > > > >> ath9k_hw_kill_interrupts+0x28/0xf0
> > > > >> [ 545.526376] [<ffffff80085a18ec>] ath_reset+0x24/0x68
> > > > >> ** 2 printk messages dropped ** [ 545.526391]
> > > > >> [<ffffff800885ad60>]
> > > > ieee80211_hw_config+0x50/0x290
> > > > >> ** 11 printk messages dropped ** [ 545.532834]
> > > > >> ath9k_hw_kill_interrupts
> > > > 793
> > > > >> [ 545.532890] ath9k_hw_enable_interrupts 821
> > > >
> > > > [ 81.876902] INFO: rcu_preempt detected stalls on CPUs/tasks:
> > > > [ 81.876912] Tasks blocked on level-0 rcu_node (CPUs 0-7): P0
> > > > [ 81.876932] (detected by 4, t=60002 jiffies, g=1873, c=1872, q=4967)
> > > > [ 81.876936] swapper/4 R running task 0 0 1
> > > > 0x00000000
> > > > [ 81.876941] 0000000000000001 ffffffff810725f6 ffff88017edbc240
> > > > ffffffff81a3dc40
> > > > [ 81.876945] ffffffff81101e46 ffff88025ef173c0 ffffffff81a3dc40
> > > > ffffffff81a3dc40
> > > > [ 81.876948] 00000000ffffffff ffffffff810a7333 ffff88017ecee698
> > > > ffff88017edbc240
> > > > [ 81.876951] Call Trace:
> > > > [ 81.876970] <IRQ>
> > > > [ 81.876979] [<ffffffff810725f6>] ? sched_show_task+0xd6/0x140
> > > > [ 81.876983] [<ffffffff81101e46>] ?
> > > > rcu_print_detail_task_stall_rnp+0x40/0x61
> > > > [ 81.876989] [<ffffffff810a7333>] ? rcu_check_callbacks+0x6b3/0x8c0
> > > > [ 81.876993] [<ffffffff810b8350>] ?
> tick_sched_handle.isra.14+0x40/0x40
> > > > [ 81.876996] [<ffffffff810aa4c3>] ? update_process_times+0x23/0x50
> > > > [ 81.876999] [<ffffffff810b8383>] ? tick_sched_timer+0x33/0x60
> > > > [ 81.877002] [<ffffffff810aaf09>] ? __hrtimer_run_queues+0xb9/0x150
> > > > [ 81.877004] [<ffffffff810ab198>] ? hrtimer_interrupt+0x98/0x1a0
> > > > [ 81.877008] [<ffffffff81031b1e>] ?
> > > > smp_trace_apic_timer_interrupt+0x5e/0x90
> > > > [ 81.877012] [<ffffffff815b31bf>] ? apic_timer_interrupt+0x7f/0x90
> > > > [ 81.877013] <EOI>
> > > > [ 81.877017] [<ffffffff8147f28d>] ? cpuidle_enter_state+0x13d/0x1f0
> > > > [ 81.877019] [<ffffffff8147f289>] ? cpuidle_enter_state+0x139/0x1f0
> > > > [ 81.877021] [<ffffffff81088c19>] ? cpu_startup_entry+0x139/0x210
> > > > [ 81.877027] [<ffffffff8102fc9e>] ? start_secondary+0x13e/0x170
> > > > [ 81.877029] swapper/4 R running task 0 0 1
> > > > 0x00000000
> > > > [ 81.877032] 0000000000000001 ffffffff810725f6 ffff88017edbc240
> > > > ffffffff81a3dc40
> > > > [ 81.877035] ffffffff81101e46 ffff88025ef173c0 ffffffff81a3dc40
> > > > ffffffff81a3dc40
> > > > [ 81.877038] 00000000ffffffff ffffffff810a7368 ffff88017ecee698
> > > > ffff88017edbc240
> > > > [ 81.877041] Call Trace:
> > > > [ 81.877045] <IRQ>
> > > > [ 81.877049] [<ffffffff810725f6>] ? sched_show_task+0xd6/0x140
> > > > [ 81.877051] [<ffffffff81101e46>] ?
> > > > rcu_print_detail_task_stall_rnp+0x40/0x61
> > > > [ 81.877055] [<ffffffff810a7368>] ? rcu_check_callbacks+0x6e8/0x8c0
> > > > [ 81.877058] [<ffffffff810b8350>] ?
> tick_sched_handle.isra.14+0x40/0x40
> > > > [ 81.877060] [<ffffffff810aa4c3>] ? update_process_times+0x23/0x50
> > > > [ 81.877063] [<ffffffff810b8383>] ? tick_sched_timer+0x33/0x60
> > > > [ 81.877065] [<ffffffff810aaf09>] ? __hrtimer_run_queues+0xb9/0x150
> > > > [ 81.877068] [<ffffffff810ab198>] ? hrtimer_interrupt+0x98/0x1a0
> > > > [ 81.877070] [<ffffffff81031b1e>] ?
> > > > smp_trace_apic_timer_interrupt+0x5e/0x90
> > > > [ 81.877073] [<ffffffff815b31bf>] ? apic_timer_interrupt+0x7f/0x90
> > > > [ 81.877074] <EOI>
> > > > [ 81.877076] [<ffffffff8147f28d>] ? cpuidle_enter_state+0x13d/0x1f0
> > > > [ 81.877078] [<ffffffff8147f289>] ? cpuidle_enter_state+0x139/0x1f0
> > > > [ 81.877080] [<ffffffff81088c19>] ? cpu_startup_entry+0x139/0x210
> > > > [ 81.877084] [<ffffffff8102fc9e>] ? start_secondary+0x13e/0x170
> > > > [ 91.132787] INFO: rcu_preempt detected expedited stalls on
> > > > CPUs/tasks: { P0 } 63785 jiffies s: 505 root: 0x0/T
> > > > [ 91.132796] blocking rcu_node structures:
> > > >
> > > > >>
> > > > >>
> > > > >> But if we have less debug prints it does not reach EP handler
> > > > >> sometimes, due to following Condition in "kernel/irq/chip.c" in
> > > > >> function handle_simple_irq
> > > > >>
> > > > >> if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) {
> > > > >> desc->istate |= IRQS_PENDING;
> > > > >> goto out_unlock;
> > > > >> }
> > > > >> Here irqd_irq_disabled is being set to 1.
> > > > >>
> > > > >> With lesser debug prints it stops after following prints:
> > > > >> root@Xilinx-ZCU102-2016_3:~# iw dev wlan0 scan
> > > > >> [ 54.781045] ath9k_hw_kill_interrupts 793
> > > > >> [ 54.785007] ath9k_hw_kill_interrupts 793
> > > > >> [ 54.792535] ath9k_hw_enable_interrupts 821
> > > > >> [ 54.796642] ath9k_hw_enable_interrupts 825
> > > > >> [ 54.800807] ath9k_hw_enable_interrupts 832
> > > > >> [ 54.804973] AR_SREV_9100 0
> > > > >> [ 54.807663] ath9k_hw_enable_interrupts 848
> > > > >> [ 54.811843] ath9k_hw_intrpend 762
> > > > >> [ 54.815211] (AR_SREV_9340(ah) val 0
> > > > >> [ 54.818684] ath9k_hw_intrpend 767
> > > > >> [ 54.822078] ath_isr 603
> > > > >> [ 54.824587] ath9k_hw_kill_interrupts 793
> > > > >> [ 54.828601] ath9k_hw_enable_interrupts 821
> > > > >> [ 54.832750] ath9k_hw_enable_interrupts 825
> > > > >> [ 54.836916] ath9k_hw_enable_interrupts 832
> > > > >> [ 54.841082] AR_SREV_9100 0
> > > > >> [ 54.843772] ath9k_hw_enable_interrupts 848
> > > > >> [ 54.843775] ath9k_hw_intrpend 762
> > > > >> [ 54.851319] (AR_SREV_9340(ah) val 0
> > > > >> [ 54.854793] ath9k_hw_intrpend 767
> > > > >> [ 54.858185] ath_isr 603
> > > > >> [ 54.860696] ath9k_hw_kill_interrupts 793
> > > > >> [ 54.864776] ath9k_hw_enable_interrupts 821
> > > > >> [ 54.867061] ath9k_hw_kill_interrupts 793
> > > > >> [ 54.872870] ath9k_hw_enable_interrupts 825
> > > > >> [ 54.877036] ath9k_hw_enable_interrupts 832
> > > > >> [ 54.881202] AR_SREV_9100 0
> > > > >> [ 54.883892] ath9k_hw_enable_interrupts 848
> > > > >> [ 75.963129] INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > >> [ 75.968602] 0-...: (2 GPs behind) idle=9d5/140000000000001/0
> > > > softirq=1103/1109 fqs=519
> > > > >> [ 75.976675] (detected by 2, t=5274 jiffies, g=64, c=63, q=11)
> > > > >> [ 75.982485] Task dump for CPU 0:
> > > > >> [ 75.985696] ksoftirqd/0 R running task 0 3 2 0x00000002
> > > > >> [ 75.992726] Call trace:
> > > > >> [ 75.995165] [<ffffff8008086b3c>] __switch_to+0xc4/0xd0
> > > > >> [ 76.000281] [<ffffffc87b830500>] 0xffffffc87b830500
> > > > >> [ 139.059027] INFO: rcu_sched detected stalls on CPUs/tasks:
> > > > >> [ 139.064430] 0-...: (2 GPs behind) idle=9d5/140000000000001/0
> > > > softirq=1103/1109 fqs=2097
> > > > >> [ 139.072593] (detected by 2, t=21049 jiffies, g=64, c=63, q=11)
> > > > >> [ 139.078489] Task dump for CPU 0:
> > > > >> [ 139.081700] ksoftirqd/0 R running task 0 3 2 0x00000002
> > > > >> [ 139.088731] Call trace:
> > > > >> [ 139.091165] [<ffffff8008086b3c>] __switch_to+0xc4/0xd0 [
> > > > >> 139.096285] [<ffffffc87b830500>] 0xffffffc87b830500
> > > > >>
> > > > >>
> > > > >>>> We are not seeing any issues on 32-bit ARM platform and X86
> > > > >>>> platform.
> > > > >>> Can you collect a dmesg log (or, if the system hang means you
> > > > >>> can't collect that, a console log with "ignore_loglevel"), and "lspci -vv"
> > > > >>> output as root? That should have clues about whether the INTx
> > > > >>> got routed correctly. /proc/interrupts should also show
> > > > >>> whether we're receiving interrupts from the device.
> > > > >> Here is the lspci output:
> > > > >> 00:00.0 PCI bridge: Xilinx Corporation Device d022 (prog-if 00
> > > > >> [Normal
> > > > decode])
> > > > >> Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV-
> VGASnoop-
> > > > ParErr- Stepping- SERR- FastB2B- DisINTx-
> > > > >> Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast
> >TAbort-
> > > > <TAbort- <MAbort- >SERR- <PERR- INTx-
> > > > >> Latency: 0
> > > > >> Interrupt: pin A routed to IRQ 224
> > > > >> Bus: primary=00, secondary=01, subordinate=0c, sec-latency=0
> > > > >> I/O behind bridge: 00000000-00000fff
> > > > >> Memory behind bridge: e0000000-e00fffff
> > > > >> Prefetchable memory behind bridge: 00000000fff00000-
> > > > 00000000000fffff
> > > > >> Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast
> >TAbort-
> > > > <TAbort- <MAbort- <SERR- <PERR-
> > > > >> BridgeCtl: Parity- SERR- NoISA- VGA- MAbort- >Reset- FastB2B-
> > > > >> PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
> > > > >> Capabilities: [40] Power Management version 3
> > > > >> Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
> > > > PME(D0+,D1+,D2+,D3hot+,D3cold-)
> > > > >> Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0
> PME-
> > > > >> Capabilities: [60] Express (v2) Root Port (Slot-), MSI 00
> > > > >> DevCap: MaxPayload 256 bytes, PhantFunc 0
> > > > >> ExtTag- RBE+
> > > > >> DevCtl: Report errors: Correctable- Non-Fatal- Fatal-
> > > > Unsupported-
> > > > >> RlxdOrd+ ExtTag- PhantFunc- AuxPwr-
> NoSnoop+
> > > > >> MaxPayload 128 bytes, MaxReadReq 512 bytes
> > > > >> DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq-
> AuxPwr-
> > > > TransPend+
> > > > >> LnkCap: Port #0, Speed 5GT/s, Width x2, ASPM not
> supported,
> > > > Exit Latency L0s unlimited, L1 unlimited
> > > > >> ClockPM- Surprise- LLActRep- BwNot+
> ASPMOptComp+
> > > > >> LnkCtl: ASPM Disabled; RCB 64 bytes Disabled-
> CommClk-
> > > > >> ExtSynch- ClockPM- AutWidDis- BWInt-
> AutBWInt-
> > > > >> LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+
> > > > DLActive- BWMgmt- ABWMgmt-
> > > > >> RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal-
> PMEIntEna-
> > > > CRSVisible+
> > > > >> RootCap: CRSVisible+
> > > > >> RootSta: PME ReqID 0000, PMEStatus- PMEPending-
> > > > >> DevCap2: Completion Timeout: Range B, TimeoutDis+,
> LTR-,
> > > > OBFF Not Supported ARIFwd-
> > > > >> DevCtl2: Completion Timeout: 50us to 50ms,
> TimeoutDis-, LTR-,
> > > > OBFF Disabled ARIFwd-
> > > > >> LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance-
> SpeedDis-
> > > > >> Transmit Margin: Normal Operating Range,
> > > > EnterModifiedCompliance- ComplianceSOS-
> > > > >> Compliance De-emphasis: -6dB
> > > > >> LnkSta2: Current De-emphasis Level: -3.5dB,
> > > > EqualizationComplete-, EqualizationPhase1-
> > > > >> EqualizationPhase2-, EqualizationPhase3-,
> > > > LinkEqualizationRequest-
> > > > >> Capabilities: [100 v1] Device Serial Number 00-00-00-00-00-00-
> 00-00
> > > > >> Capabilities: [10c v1] Virtual Channel
> > > > >> Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
> > > > >> Arb: Fixed- WRR32- WRR64- WRR128-
> > > > >> Ctrl: ArbSelect=Fixed
> > > > >> Status: InProgress-
> > > > >> VC0: Caps: PATOffset=00 MaxTimeSlots=1
> RejSnoopTrans-
> > > > >> Arb: Fixed- WRR32- WRR64- WRR128-
> TWRR128-
> > > > WRR256-
> > > > >> Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
> > > > >> Status: NegoPending- InProgress-
> > > > >> Capabilities: [128 v1] Vendor Specific Information: ID=1234
> > > > >> Rev=1
> > > > >> Len=018 <?>
> > > > >>
> > > > >> 01:00.0 Network controller: Qualcomm Atheros AR93xx Wireless
> > > > >> Network
> > > > Adapter (rev 01)
> > > > >> Subsystem: Qualcomm Atheros Device 3112
> > > > >> Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV-
> VGASnoop-
> > > > ParErr- Stepping- SERR- FastB2B- DisINTx-
> > > > >> Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast
> >TAbort-
> > > > <TAbort- <MAbort- >SERR- <PERR- INTx-
> > > > >> Latency: 0, Cache Line Size: 128 bytes
> > > > >> Interrupt: pin A routed to IRQ 224
> > > > >> Region 0: Memory at e0000000 (64-bit, non-prefetchable)
> [size=128K]
> > > > >> [virtual] Expansion ROM at e0020000 [disabled] [size=64K]
> > > > >> Capabilities: [40] Power Management version 3
> > > > >> Flags: PMEClk- DSI- D1+ D2- AuxCurrent=375mA
> > > > PME(D0+,D1+,D2-,D3hot+,D3cold-)
> > > > >> Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0
> PME-
> > > > >> Capabilities: [50] MSI: Enable- Count=1/4 Maskable+ 64bit+
> > > > >> Address: 0000000000000000 Data: 0000
> > > > >> Masking: 00000000 Pending: 00000000
> > > > >> Capabilities: [70] Express (v2) Endpoint, MSI 00
> > > > >> DevCap: MaxPayload 128 bytes, PhantFunc 0,
> Latency
> > > > L0s <1us, L1 <8us
> > > > >> ExtTag- AttnBtn- AttnInd- PwrInd- RBE+
> FLReset-
> > > > SlotPowerLimit 0.000W
> > > > >> DevCtl: Report errors: Correctable- Non-Fatal- Fatal-
> > > > Unsupported-
> > > > >> RlxdOrd+ ExtTag- PhantFunc- AuxPwr-
> NoSnoop-
> > > > >> MaxPayload 128 bytes, MaxReadReq 512 bytes
> > > > >> DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq-
> AuxPwr-
> > > > TransPend-
> > > > >> LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1,
> Exit
> > > > Latency L0s <2us, L1 <64us
> > > > >> ClockPM- Surprise- LLActRep- BwNot-
> ASPMOptComp-
> > > > >> LnkCtl: ASPM Disabled; RCB 64 bytes Disabled-
> CommClk-
> > > > >> ExtSynch- ClockPM- AutWidDis- BWInt-
> AutBWInt-
> > > > >> LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+
> > > > DLActive- BWMgmt- ABWMgmt-
> > > > >> DevCap2: Completion Timeout: Not Supported,
> TimeoutDis+,
> > > > LTR-, OBFF Not Supported
> > > > >> DevCtl2: Completion Timeout: 50us to 50ms,
> TimeoutDis-, LTR-,
> > > > OBFF Disabled
> > > > >> LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance-
> > > > SpeedDis-
> > > > >> Transmit Margin: Normal Operating Range,
> > > > EnterModifiedCompliance- ComplianceSOS-
> > > > >> Compliance De-emphasis: -6dB
> > > > >> LnkSta2: Current De-emphasis Level: -6dB,
> > > > EqualizationComplete-, EqualizationPhase1-
> > > > >> EqualizationPhase2-, EqualizationPhase3-,
> > > > LinkEqualizationRequest-
> > > > >> Capabilities: [100 v1] Advanced Error Reporting
> > > > >> UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt-
> UnxCmplt-
> > > > RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
> > > > >> UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt-
> UnxCmplt-
> > > > RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
> > > > >> UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt-
> UnxCmplt-
> > > > RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
> > > > >> CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout-
> > > > NonFatalErr-
> > > > >> CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout-
> > > > NonFatalErr+
> > > > >> AERCap: First Error Pointer: 00, GenCap-
> CGenEn-
> > > > ChkCap- ChkEn-
> > > > >> Capabilities: [140 v1] Virtual Channel
> > > > >> Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
> > > > >> Arb: Fixed- WRR32- WRR64- WRR128-
> > > > >> Ctrl: ArbSelect=Fixed
> > > > >> Status: InProgress-
> > > > >> VC0: Caps: PATOffset=00 MaxTimeSlots=1
> RejSnoopTrans-
> > > > >> Arb: Fixed- WRR32- WRR64- WRR128-
> TWRR128-
> > > > WRR256-
> > > > >> Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
> > > > >> Status: NegoPending- InProgress-
> > > > >> Capabilities: [300 v1] Device Serial Number 00-00-00-00-00-00-
> 00-00
> > > > >> Kernel driver in use: ath9k
> > > > >>
> > > > >> Here is the cat /proc/interrupts (after we do interface up):
> > > > >>
> > > > >> root@:~# ifconfig wlan0 up
> > > > >> [ 1548.926601] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not
> > > > >> ready root@Xilinx-ZCU102-2016_3:~# cat /proc/interrupts
> > > > >> CPU0 CPU1 CPU2 CPU3
> > > > >> 1: 0 0 0 0 GICv2 29 Edge arch_timer
> > > > >> 2: 19873 20058 19089 17435 GICv2 30 Edge
> arch_timer
> > > > >> 12: 0 0 0 0 GICv2 156 Level zynqmp-dma
> > > > >> 13: 0 0 0 0 GICv2 157 Level zynqmp-dma
> > > > >> 14: 0 0 0 0 GICv2 158 Level zynqmp-dma
> > > > >> 15: 0 0 0 0 GICv2 159 Level zynqmp-dma
> > > > >> 16: 0 0 0 0 GICv2 160 Level zynqmp-dma
> > > > >> 17: 0 0 0 0 GICv2 161 Level zynqmp-dma
> > > > >> 18: 0 0 0 0 GICv2 162 Level zynqmp-dma
> > > > >> 19: 0 0 0 0 GICv2 163 Level zynqmp-dma
> > > > >> 20: 0 0 0 0 GICv2 164 Level Mali_GP_MMU,
> > > > Mali_GP, Mali_PP0_MMU, Mali_PP0, Mali_PP1_MMU, Mali_PP1
> > > > >> 30: 0 0 0 0 GICv2 95 Level eth0, eth0
> > > > >> 206: 314 0 0 0 GICv2 49 Level cdns-i2c
> > > > >> 207: 40 0 0 0 GICv2 50 Level cdns-i2c
> > > > >> 209: 0 0 0 0 GICv2 150 Level nwl_pcie:misc
> > > > >> 214: 12 0 0 0 GICv2 47 Level ff0f0000.spi
> > > > >> 215: 0 0 0 0 GICv2 58 Level ffa60000.rtc
> > > > >> 216: 0 0 0 0 GICv2 59 Level ffa60000.rtc
> > > > >> 217: 0 0 0 0 GICv2 165 Level ahci-
> > > > ceva[fd0c0000.ahci]
> > > > >> 218: 61 0 0 0 GICv2 81 Level mmc0
> > > > >> 219: 0 0 0 0 GICv2 187 Level arm-smmu global
> > fault
> > > > >> 220: 471 0 0 0 GICv2 53 Level xuartps
> > > > >> 223: 0 0 0 0 GICv2 154 Level fd4c0000.dma
> > > > >> 224: 3 0 0 0 dummy 1 Edge ath9k
> > > > >> 225: 0 0 0 0 GICv2 97 Level xhci-hcd:usb1
> > > > >>
> > > > >> Regards,
> > > > >> Bharat
> > >
> --
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