linux-kernel - Re: [PATCH v2 2/6] genirq: fix irqchip_set_wake_parent if IRQCHIP_SKIP_SET

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Message-ID: <55CDC089.1060309@ti.com>
Date:	Fri, 14 Aug 2015 13:18:49 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Marc Zyngier <marc.zyngier@....com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"tony@...mide.com" <tony@...mide.com>, <sudeep.holla@....com>
CC:	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"nsekhar@...com" <nsekhar@...com>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"balbi@...com" <balbi@...com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/6] genirq: fix irqchip_set_wake_parent if IRQCHIP_SKIP_SET_WAKE

On 08/13/2015 03:58 PM, Grygorii Strashko wrote:
> On 08/13/2015 01:31 PM, Grygorii Strashko wrote:
>> On 08/13/2015 01:01 PM, Marc Zyngier wrote:
>>> On 12/08/15 18:45, Grygorii Strashko wrote:
>>>> The irqchip_set_wake_parent should not fail if IRQ chip
>>>> specifies IRQCHIP_SKIP_SET_WAKE. Otherwise, IRQ wakeup
>>>> configuration can't be propagated properly through IRQ
>>>> domains hierarchy.
>>>>
>>>> In case of TI OMAP DRA7 the issue reproduced with following
>>>> configuration:
>>>> ARM GIC<-OMAP wakeupgen<-TI CBAR<-GPIO<-GPIO pcf857x<-gpio_key
>>>>
>>>> gpio_key is wakeup source
>>>>
>>>> Failure is reproduced during suspend/resume to RAM:
>>>> suspend:
>>>>    - gpio_keys_suspend
>>>>      enable_irq_wake
>>>>        + pcf857x_irq_set_wake
>>>>          + omap_gpio_wake_enable
>>>>            + TI CBAR irq_chip_set_wake_parent
>>>>              + OMAP wakeupgen has no .irq_set_wake()
>>>
>>> Most importantly, wakeupgen has IRQCHIP_SKIP_SET_WAKE set.
>>>
>>>>              and -ENOSYS will be returned
>>>>
>>>> resume:
>>>>    - gpio_keys_resume
>>>>      + disable_irq_wake
>>>>        + irq_set_irq_wake
>>>>          + WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
>>>>
>>>> Fixes: 08b55e2a9208 ('genirq: Add irqchip_set_wake_parent')
>>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>>>> ---
>>>>    kernel/irq/chip.c | 4 ++++
>>>>    1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
>>>> index 6de638b..bdb1b9d 100644
>>>> --- a/kernel/irq/chip.c
>>>> +++ b/kernel/irq/chip.c
>>>> @@ -1024,6 +1024,10 @@ int irq_chip_set_vcpu_affinity_parent(struct
>>>> irq_data *data, void *vcpu_info)
>>>>    int irq_chip_set_wake_parent(struct irq_data *data, unsigned int on)
>>>>    {
>>>>        data = data->parent_data;
>>>> +
>>>> +    if (irq_data_get_irq_chip(data)->flags & IRQCHIP_SKIP_SET_WAKE)
>>>> +        return 0;
>>>> +
>>>>        if (data->chip->irq_set_wake)
>>>>            return data->chip->irq_set_wake(data, on);
>>>>
>>>>
>>>
>>> We have a more general issue with chip flags, and how they combine
>>> within a stack of irqchips.
>>
>> Indeed. Problem looks similar to IRQCHIP_MASK_ON_SUSPEND flag usage.
>>
>>>
>>> What if you remove the irq_chip_set_wake_parent from the crossbar
>>> driver, and instead set IRQCHIP_SKIP_SET_WAKE?
>>
>> I've thought about this and it should work for me.
>> One question - what if crossbar will be not the last one in
>> IRQ domains hierarchy?
>>
> 
> I can confirm, if I revert this patch, add IRQCHIP_SKIP_SET_WAKE to
> the crossbar and remove irq_chip_set_wake_parent wakeups still works.
> What do you prefer me to do: add additional patch for the crossbar,
> drop/keep this patch?
> 

OK. There are two possibilities to fix set_wake functionality for TI OMAPs
where below HW configurations are used:
  OMAP4/5: GIC <- OMAP wakeupgen
  DRA7: GIC <- OMAP wakeupgen <- TI CBAR


1) ensure that IRQCHIP_SKIP_SET_WAKE flag is set only for GIC and
use irq_chip_set_wake_parent() in both wakeupgen and crossbar 
 [this patch is required]

2) ensure that IRQCHIP_SKIP_SET_WAKE flag is set and drop 
.irq_set_wake()/irq_chip_set_wake_parent() for all IRQ chips
in IRQ domains hierarchy.
 [this patch can be dropped]

I'm going to select approach 2 and re-send.


-- 
regards,
-grygorii
--
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