linux-kernel - Re: [PATCH v2 1/6] genirq: fix irq_chip_retrigger

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Date:	Thu, 13 Aug 2015 10:26:30 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Grygorii Strashko <grygorii.strashko@...com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"tony@...mide.com" <tony@...mide.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>,
	Jiang Liu <jiang.liu@...ux.intel.com>
Subject: Re: [PATCH v2 1/6] genirq: fix irq_chip_retrigger_hierarchy

[adding Jiang to the cc list]

On 12/08/15 18:45, Grygorii Strashko wrote:
> Now irq_chip_retrigger_hierarchy() returns -ENOSYS if it
> was not able to find at least one .irq_retrigger() callback
> implemented in IRQ domain hierarchy. As result, IRQ
> re-triggering is not working now on ARM (TI OMAP) where
> ARM GIC is not implemented this callback.
> The .irq_retrigger() is optional (see check_irq_resend())
> and there are no reasons to fail if it was not found, hence
> lets return 0 in this case.
> 
> In case of TI OMAP DRA7 the following IRQ hierarchy is defined:
> ARM GIC <- OMAP wakeupgen <- TI CBAR
> 
> Failure is reproduced during resume from suspend to RAM:
> - wakeup by IRQx
> - suspend_enter
>   + arch_suspend_enable_irqs
>     + handle_fasteoi_irq
>       + irq_may_run
>         + irq_pm_check_wakeup
>           + irq_disable(IRQx)
>   + dpm_resume_noirq()
>     + resume_device_irqs
>       + resume_irqs
>         + resume_irq
>           + __enable_irq <== IRQx is not re-triggered
> 
> Fixes: 85f08c17de26 ('genirq: Introduce helper functions...')
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
> ---
>  kernel/irq/chip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index 27f4332..6de638b 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -997,7 +997,7 @@ int irq_chip_retrigger_hierarchy(struct irq_data *data)
>  		if (data->chip && data->chip->irq_retrigger)
>  			return data->chip->irq_retrigger(data);
>  
> -	return -ENOSYS;
> +	return 0;
>  }
>  
>  /**
> 

I think this makes sense. Not having an irq_retrigger or having an
irq_retrigger that returns zero are the same thing.

Actually, we don't even distinguish between a retrigger that
successfully poked the HW, and a retrigger that returned an error. Both
are considered to not to require a SW retrigger... maybe we should fix
that too. Jiang, Thomas?

Anyway, for this patch:

Reviewed-by: Marc Zyngier <marc.zyngier@....com>

	M.
-- 
Jazz is not dead. It just smells funny...
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