linux-kernel - Re: [PATCH] gpio: omap: fix irq triggering in smart-idle wakeup mode

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Date:	Mon, 18 Apr 2016 18:57:43 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Tony Lindgren <tony@...mide.com>,
	santosh shilimkar <santosh.shilimkar@...cle.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Sekhar Nori <nsekhar@...com>,
	Linux-OMAP <linux-omap@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Roger Quadros <rogerq@...com>
Subject: Re: [PATCH] gpio: omap: fix irq triggering in smart-idle wakeup mode

On 04/15/2016 09:54 PM, Tony Lindgren wrote:
> * santosh shilimkar <santosh.shilimkar@...cle.com> [160415 08:22]:
>> On 4/15/2016 2:26 AM, Grygorii Strashko wrote:
>>>
>>> Santosh, Tony, do you want me to perform any additional actions regarding this patch?
>>>
>> This patch should be run across family of SOCs to make
>> sure wakeup works on all of those if not done already
> 
> Also, I'm not sure if we can just drop this code in question.
> 
> After this patch, what function updates the GPIO wkup_en registers
> depending on enable_irq_wake()/disable_irq_wake()?
> 

The main purpose of this patch is to *not* modify GPIO wkup_en registers
depending of enable_irq_wake()/disable_irq_wake() :), instead all
non wake up IRQs should be masked during suspend.

The GPIO wkup_en registers should be always in sync with GPIO irq_en when
GPIO IP is in smart-idle wakeup mode. And this is done now from 
omap_gpio_unmask_irq/omap_gpio_mask_irq(). See also [1].

In general, it is more or less similar to GIC + wakeupgen:
- during normal work (including cpuidle) GIC irq_en and Wakeupgen wkup_en
should be in sync always
- during suspend - only IRQs, marked as wake up sources, should be left
unmasked.

Also, I've found old thread [2] where Santosh proposed to use IRQCHIP_MASK_ON_SUSPEND.
And it was not possible, at that time, but now IRQCHIP_MASK_ON_SUSPEND can be used :),
because OMAP GPIO driver was switched to use generic irq handler instead of chained, so
now OMAP GPIO irqs are properly handled by IRQ PM core.  
[chained irqs (and chained irq handles) are not disabled during suspend/resume and they are
 not maintained by IRQ PM core as result they can trigger way too early on resume when
 OMAP GPIO is not ready/powered.]

I've tested it on: am57x-evm, am437x-idk-evm, omap4-panda

[1] https://lkml.org/lkml/2016/4/12/676
[2] https://lkml.org/lkml/2012/8/26/1
    https://groups.google.com/forum/#!msg/linux.kernel/iXJ5Y568B3Q/hZ39bSlcs0kJ

-- 
regards,
-grygorii