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:[email protected]]
>Sent: Tuesday, December 24, 2013 8:31 AM
>To: Huang Yongcai-B20788
>Cc: [email protected]; [email protected]
>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?
>
>>
>> Signed-off-by: Anson Huang <[email protected]>
>> ---
>> drivers/input/keyboard/gpio_keys.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/input/keyboard/gpio_keys.c
>> b/drivers/input/keyboard/gpio_keys.c
>> index 2db1324..aadb1db 100644
>> --- a/drivers/input/keyboard/gpio_keys.c
>> +++ b/drivers/input/keyboard/gpio_keys.c
>> @@ -473,6 +473,8 @@ static int gpio_keys_setup_key(struct
>> platform_device *pdev,
>>
>> isr = gpio_keys_gpio_isr;
>> irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
>> + if (bdata->button->wakeup)
>> + irqflags |= IRQF_NO_SUSPEND;
>>
>> } else {
>> if (!button->irq) {
>> --
>> 1.7.9.5
>>
>>
>
>--
>Dmitry
>
