linux-kernel - Re: [PATCH] power: Add legacy pm ops usage warning

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Date:	Sat, 02 Nov 2013 00:04:50 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Shuah Khan <shuah.kh@...sung.com>
Cc:	pavel@....cz, len.brown@...el.com, gregkh@...uxfoundation.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	shuahkhan@...il.com
Subject: Re: [PATCH] power: Add legacy pm ops usage warning

On Friday, November 01, 2013 09:07:04 AM Shuah Khan wrote:
> Add legacy pm_ops usage checks to device_pm_add() when a device gets added
> to PM core's list of active devices. If legacy pm_ops usage is found at its
> class, bus, driver level, print warning message to indicate the driver code
> needs updating to use dev pm ops interfaces. This will help serve as a way
> to track drivers that still use legacy pm ops and fix them.

I think it would be much better to do these checks during bus type, class or
driver registration, because if you register a bus type with legacy PM, for
example, the check in device_pm_add() will trigger for all devices with that
bus type.

Thanks!

> Signed-off-by: Shuah Khan <shuah.kh@...sung.com>
> ---
>  drivers/base/power/main.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 9f098a8..4dc26dc 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -112,6 +112,23 @@ void device_pm_unlock(void)
>  }
>  
>  /**
> + * check for lgeacy pm_ops usage and warn
> + */
> +static void device_legacy_pm_ops_check(struct device *dev)
> +{
> +	char *info = "Please update driver to use dev pm_ops";
> +
> +	if (dev->class && (dev->class->suspend || dev->class->resume))
> +		dev_warn(dev, "Driver uses legacy class pm ops - %s\n", info);
> +
> +	if (dev->bus && (dev->bus->suspend || dev->bus->resume))
> +		dev_warn(dev, "Driver uses legacy bus pm ops - %s\n", info);
> +
> +	if (dev->driver && (dev->driver->suspend || dev->driver->resume))
> +		dev_warn(dev, "Driver uses legacy pm ops - %s\n", info);
> +}
> +
> +/**
>   * device_pm_add - Add a device to the PM core's list of active devices.
>   * @dev: Device to add to the list.
>   */
> @@ -123,6 +140,7 @@ void device_pm_add(struct device *dev)
>  	if (dev->parent && dev->parent->power.is_prepared)
>  		dev_warn(dev, "parent %s should not be sleeping\n",
>  			dev_name(dev->parent));
> +	device_legacy_pm_ops_check(dev);
>  	list_add_tail(&dev->power.entry, &dpm_list);
>  	mutex_unlock(&dpm_list_mtx);
>  }
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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