Re: [PATCH] Input: gpio_keys: support wakeup system from freeze mode

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Anson,

On Tue, Dec 24, 2013 at 02:29:54AM +0000, Anson.Huang@freescale.com
wrote:
> Hi, Dmitry
> 
> 	See below:
> 
> Best Regards.  Anson huang 黄勇才   Freescale Semiconductor Shanghai
> 上海浦东新区亮景路192号A座2楼 201203 Tel:021-28937058
> 
> 
> >-----Original Message----- From: Dmitry Torokhov
> >[mailto:dmitry.torokhov@gmail.com] Sent: Tuesday, December 24, 2013
> >8:31 AM To: Huang Yongcai-B20788 Cc: sachin.kamat@linaro.org;
> >linux-input@vger.kernel.org Subject: Re: [PATCH] Input: gpio_keys:
> >support wakeup system from freeze mode
> >
> >Hi Anson,
> >
> >On Mon, Dec 23, 2013 at 01:21:20PM -0500, Anson Huang wrote:
> >> For "freeze" mode of suspend, cpu will go into idle and those
> >> wakeup sources' irq should NOT be disabled during devices suspend,
> >> so we need to add IRQF_NO_SUSPEND flag for those wakeup sources.
> >>
> >> Steps to test this patch:
> >>
> >> 1. echo freeze > /sys/power/state; 2. press gpio key which has
> >> wakeup function, then system will resume.
> >
> >I do no think this is correct approach, otheriwse every driver that
> >can be a wakeup source would have to use IRQF_NO_SUSPEND flag. The
> >driver does use enable_irq_wake() in its suspend path, and platform
> >code should perform all necessary work for this IRQ to be usable as a
> >wakeup source.
> >
> >Thanks.
> 
> 
> From the suspend flow, we can see that kernel will disable all
> devices' irq unless its IRQF_NO_SUSPEND flag is set. For freeze mode,
> as cpu will be in idle, SOC is not in low power mode, that means
> freeze mode equals cpu in idle and devices in suspend. The wakeup
> source must come from GIC. Yes, for normal standby/mem mode's suspend,
> the enable_irq_wake will make everything done for waking up a system,
> in gic_set_wake routine, it will call extern irq chip's wakeup
> function, but for freeze mode, the wakeup process is same as normal
> wakeup from cpu idle, so the wakeup source must be not masked in gic. 
> 
> Take our i.MX6 SOC for example, there is GPC module which is used to
> wake up SOC from STOP mode(low power mode of SOC), normal standby/mem
> mode suspend, the wakeup source's enable_irq_wake will set GPC to
> monitor these irq source and wakeup system from STOP mode when there
> is an wakeup event. But for freeze mode, kernel's suspend flow will
> not finish the SOC's low level power management, the secondary CPUs
> are even not disabled, kernel just suspend the devices and put CPU
> into idle and waiting for wakeup even, in GIC's gic_set_wake routine,
> it only calls our GPC's imx_gpc_irq_set_wake, here comes the problem,
> as our SOC is not entering STOP mode, GPC has no use to set this
> wakeup source enabled. So either we should enable GIC's wakeup in GIC
> driver, or just set this flag to make kernel do NOT disable this
> wakeup source's irq when executing a freeze mode suspend.
>
> Otherwise, we need to modify the GIC driver?

Yes, I believe it is the task of platform code to make sure that
enable_irq_wake() enables irq wakeup properly, be it suspend or
hibernate.

Thanks.

-- 
Dmitry
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html