linux-kernel - Re: [PATCH] driver-core: platform: automatically mark wakeup devices

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Date:	Mon, 18 Jan 2016 15:47:27 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Thierry Reding <treding@...dia.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>, linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] driver-core: platform: automatically mark wakeup devices

On Sunday, January 17, 2016 06:11:38 PM Dmitry Torokhov wrote:
> When probing platform drivers let's check if corresponding devices have
> "wakeup-source" property defined (either in device tree, ACPI, or static
> platform properties) and automatically enable such devices as wakeup
> sources for the system. This will help us standardize on the name for this
> property and reduce amount of boilerplate code in the drivers.

ACPI has other ways of telling the OS that the device is wakeup-capable,
but I guess the property in question can be used too (as long as it is
consistent with the other methods).

> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
>  drivers/base/platform.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 1dd6d3b..d14071a 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -514,9 +514,14 @@ static int platform_drv_probe(struct device *_dev)
>  
>  	ret = dev_pm_domain_attach(_dev, true);
>  	if (ret != -EPROBE_DEFER && drv->probe) {
> +		bool wakeup = device_property_read_bool(_dev, "wakeup-source");
> +
> +		device_init_wakeup(_dev, wakeup);

But I'm wondering if this should be device_set_wakeup_capable(dev, true) rather?

device_init_wakeup() additionally sets the default in sysfs to "do wakeup"
which in principle may unblock spurious wakeups on some systems.

>  		ret = drv->probe(dev);
> -		if (ret)
> +		if (ret) {
> +			device_init_wakeup(_dev, false);
>  			dev_pm_domain_detach(_dev, true);
> +		}
>  	}
>  
>  	if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
> @@ -540,6 +545,8 @@ static int platform_drv_remove(struct device *_dev)
>  
>  	if (drv->remove)
>  		ret = drv->remove(dev);
> +
> +	device_init_wakeup(_dev, false);
>  	dev_pm_domain_detach(_dev, true);
>  
>  	return ret;
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.