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Date:	Fri, 4 Dec 2015 17:59:29 +0200
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Sudeep Holla <sudeep.holla@....com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>
Subject: Re: [PATCH 2/2] pinctrl: single: remove misuse of IRQF_NO_SUSPEND
 flag

On 12/04/2015 05:35 PM, Tony Lindgren wrote:
> * Grygorii Strashko <grygorii.strashko@...com> [151204 02:45]:
>> On 12/03/2015 11:37 PM, Tony Lindgren wrote:
>>> * Grygorii Strashko <grygorii.strashko@...com> [151203 10:36]:
>>>>
>>>> I think, this patch should not break our wake-up functionality.
>>>> It will just change the moment when pcs_irq_handler() will be called:
>>>>
>>>> before this change:
>>>> - suspend_enter()
>>>>    ....
>>>>    - arch_suspend_enable_irqs();
>>>>      - ^ right here
>>>>
>>>> after this change:
>>>> - suspend_enter()
>>>>    ....
>>>>    dpm_resume_noirq()
>>>>    - resume_device_irqs()
>>>>      ^ here
>>>>
>>>> Correct? And as for me this is more safe.
>>>
>>> I think there's more to it though. With both applied, it produces this on
>>> coming back up from suspend:
>>>
>>> PM: noirq resume of devices complete after 18.127 msecs
>>> ------------[ cut here ]------------
>>> WARNING: CPU: 0 PID: 123 at kernel/irq/manage.c:605 irq_set_irq_wake+0xbc/0xfc()
>>> Unbalanced IRQ 375 wake disable
>>> Modules linked in: ledtrig_default_on leds_gpio led_class rtc_twl twl4030_wdt
>>> CPU: 0 PID: 123 Comm: bash Tainted: G        W       4.4.0-rc3-dirty #2682
>>> Hardware name: Generic OMAP36xx (Flattened Device Tree)
>>> [<c0017df0>] (unwind_backtrace) from [<c0014084>] (show_stack+0x10/0x14)
>>> <c0014084>] (show_stack) from [<c03492d0>] (dump_stack+0x84/0x9c)
>>> [<c03492d0>] (dump_stack) from [<c003ca2c>] (warn_slowpath_common+0x7c/0xb8)
>>> [<c003ca2c>] (warn_slowpath_common) from [<c003ca98>] (warn_slowpath_fmt+0x30/0x40)
>>> [<c003ca98>] (warn_slowpath_fmt) from [<c009b66c>] (irq_set_irq_wake+0xbc/0xfc)
>>> [<c009b66c>] (irq_set_irq_wake) from [<c03f0f1c>] (device_wakeup_disarm_wake_irqs+0x70/0x12c)
>>> [<c03f0f1c>] (device_wakeup_disarm_wake_irqs) from [<c03ee4ac>] (dpm_resume_noirq+0x20c/0x2e4)
>>> [<c03ee4ac>] (dpm_resume_noirq) from [<c0095e94>] (suspend_devices_and_enter+0x1e4/0x6bc)
>>> [<c0095e94>] (suspend_devices_and_enter) from [<c00966c4>] (pm_suspend+0x358/0x4b8)
>>> [<c00966c4>] (pm_suspend) from [<c0094fdc>] (state_store+0x64/0xb8)
>>> [<c0094fdc>] (state_store) from [<c034b46c>] (kobj_attr_store+0x14/0x20)
>>> [<c034b46c>] (kobj_attr_store) from [<c01ea4d8>] (sysfs_kf_write+0x4c/0x50)
>>> [<c01ea4d8>] (sysfs_kf_write) from [<c01e9afc>] (kernfs_fop_write+0xbc/0x1cc)
>>> [<c01e9afc>] (kernfs_fop_write) from [<c0171c7c>] (__vfs_write+0x24/0xd8)
>>> [<c0171c7c>] (__vfs_write) from [<c0172520>] (vfs_write+0x94/0x154)
>>> [<c0172520>] (vfs_write) from [<c0172d1c>] (SyS_write+0x40/0x94)
>>> [<c0172d1c>] (SyS_write) from [<c000f760>] (ret_fast_syscall+0x0/0x1c)
>>> ---[ end trace 321b51565e161bee ]---
>>>
>>> And these both need to be applied together when we have a fix for the above
>>> as otherwise we'll get the lock recursion Sudeep mentioned in patch 2/2.
>>>
>>
>> Most probably below diff will fix above issue:
>>
>> diff --git a/arch/arm/mach-omap2/prm_common.c
>> b/arch/arm/mach-omap2/prm_common.c
>> index 3fc2cbe..69cde67 100644
>> --- a/arch/arm/mach-omap2/prm_common.c
>> +++ b/arch/arm/mach-omap2/prm_common.c
>> @@ -338,6 +338,7 @@ int omap_prcm_register_chain_handler(struct
>> omap_prcm_irq_setup *irq_setup)
>>                  ct->chip.irq_ack = irq_gc_ack_set_bit;
>>                  ct->chip.irq_mask = irq_gc_mask_clr_bit;
>>                  ct->chip.irq_unmask = irq_gc_mask_set_bit;
>> +               ct->chip.flags = IRQCHIP_SKIP_SET_WAKE;
>>
>>                  ct->regs.ack = irq_setup->ack + i * 4;
>>                  ct->regs.mask = irq_setup->mask + i * 4;
>>
>>
> 
> That fixes the warning on resume, but adds a new one during init:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at kernel/irq/pm.c:51 irq_pm_install_action+0x9c/0xec()
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc3-00001-g6a5e5ec #2694
> Hardware name: Generic OMAP36xx (Flattened Device Tree)
> [<c0017df0>] (unwind_backtrace) from [<c0014084>] (show_stack+0x10/0x14)
> [<c0014084>] (show_stack) from [<c03492f0>] (dump_stack+0x84/0x9c)
> [<c03492f0>] (dump_stack) from [<c003ca34>] (warn_slowpath_common+0x7c/0xb8)
> [<c003ca34>] (warn_slowpath_common) from [<c003cb0c>] (warn_slowpath_null+0x1c/0x24)
> [<c003cb0c>] (warn_slowpath_null) from [<c00a27d8>] (irq_pm_install_action+0x9c/0xec)
> [<c00a27d8>] (irq_pm_install_action) from [<c009ccb0>] (__setup_irq+0x434/0x5e0)
> [<c009ccb0>] (__setup_irq) from [<c009cfb0>] (request_threaded_irq+0xc4/0x15c)
> [<c009cfb0>] (request_threaded_irq) from [<c08c25e8>] (omap3_pm_init+0x10c/0x400)
> [<c08c25e8>] (omap3_pm_init) from [<c08bc66c>] (omap3_init_late+0xc/0x14)
> [<c08bc66c>] (omap3_init_late) from [<c08b5820>] (init_machine_late+0x1c/0x90)
> [<c08b5820>] (init_machine_late) from [<c0009804>] (do_one_initcall+0x80/0x1e0)
> [<c0009804>] (do_one_initcall) from [<c08b2ec4>] (kernel_init_freeable+0x218/0x2e8)
> [<c08b2ec4>] (kernel_init_freeable) from [<c064584c>] (kernel_init+0x8/0xec)
> [<c064584c>] (kernel_init) from [<c000f7f0>] (ret_from_fork+0x14/0x24)
> ---[ end trace 81093452bf564522 ]---
> 

Sorry, I can't test it right now :(
Potential fix below:
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 2dbd378..4e56fd9 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -481,7 +481,7 @@ int __init omap3_pm_init(void)
 
        /* IO interrupt is shared with mux code */
        ret = request_irq(omap_prcm_event_to_irq("io"),
-               _prcm_int_handle_io, IRQF_SHARED | IRQF_NO_SUSPEND, "pm_io",
+               _prcm_int_handle_io, IRQF_SHARED, "pm_io",
                omap3_pm_init);
        enable_irq(omap_prcm_event_to_irq("io"));
 
@@ -489,6 +489,7 @@ int __init omap3_pm_init(void)
                pr_err("pm: Failed to request pm_io irq\n");
                goto err2;
        }
+       enable_irq_wake(omap_prcm_event_to_irq("io"));
 
        ret = pwrdm_for_each(pwrdms_setup, NULL);
        if (ret) {



-- 
regards,
-grygorii
--
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