linux-kernel - RE: [PATCH 2/2] platform / ACPI: Attach/detach ACPI PM during probe/remove/shutdown

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Date:	Tue, 27 Nov 2012 05:24:46 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	"Zhang, Rui" <rui.zhang@...el.com>,
	"Svahn, Kai" <kai.svahn@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	"Lan, Tianyu" <tianyu.lan@...el.com>,
	"Lu, Aaron" <aaron.lu@...el.com>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: RE: [PATCH 2/2] platform / ACPI: Attach/detach ACPI PM during
 probe/remove/shutdown

It looks cleanest unless more abstractions are introduced for other power management providers.

Best regards/Lv Zheng

> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@...k.pl]
> Sent: Sunday, November 25, 2012 10:58 PM
> To: LKML
> Cc: Greg Kroah-Hartman; Linux PM list; ACPI Devel Maling List; Zhang, Rui;
> Svahn, Kai; Mika Westerberg; Huang, Ying; Lan, Tianyu; Zheng, Lv; Lu, Aaron;
> Grant Likely
> Subject: [PATCH 2/2] platform / ACPI: Attach/detach ACPI PM during
> probe/remove/shutdown
> 
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Drivers usually expect that the devices they are supposed to handle will be
> operational when their .probe() routines are called, but that need not be the
> case on some ACPI-based systems with ACPI-based device enumeration where
> the BIOSes don't put devices into D0 by default.  To work around this problem
> it is sufficient to change bus type .probe() routines to ensure that devices will
> be powered on before the drivers' .probe() routines run (and their .remove()
> and .shutdown() routines accordingly).
> 
> Modify platform_drv_probe() to run acpi_dev_pm_attach() for devices whose
> ACPI handles are present, so that ACPI power management is used to change
> their power states and change their power states to D0 before driver probing.
> Analogously, modify platform_drv_remove() and
> platform_drv_shutdown() to call acpi_dev_pm_detach() for those devices, so
> that they are not subject to ACPI PM any more.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/base/platform.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> Index: linux/drivers/base/platform.c
> ================================================================
> ===
> --- linux.orig/drivers/base/platform.c
> +++ linux/drivers/base/platform.c
> @@ -484,8 +484,16 @@ static int platform_drv_probe(struct dev  {
>  	struct platform_driver *drv = to_platform_driver(_dev->driver);
>  	struct platform_device *dev = to_platform_device(_dev);
> +	int ret;
> 
> -	return drv->probe(dev);
> +	if (ACPI_HANDLE(_dev))
> +		acpi_dev_pm_attach(_dev, true);
> +
> +	ret = drv->probe(dev);
> +	if (ret && ACPI_HANDLE(_dev))
> +		acpi_dev_pm_detach(_dev, true);
> +
> +	return ret;
>  }
> 
>  static int platform_drv_probe_fail(struct device *_dev) @@ -497,8 +505,13
> @@ static int platform_drv_remove(struct de  {
>  	struct platform_driver *drv = to_platform_driver(_dev->driver);
>  	struct platform_device *dev = to_platform_device(_dev);
> +	int ret;
> +
> +	ret = drv->remove(dev);
> +	if (ACPI_HANDLE(_dev))
> +		acpi_dev_pm_detach(_dev, true);
> 
> -	return drv->remove(dev);
> +	return ret;
>  }
> 
>  static void platform_drv_shutdown(struct device *_dev) @@ -507,6 +520,8
> @@ static void platform_drv_shutdown(struct
>  	struct platform_device *dev = to_platform_device(_dev);
> 
>  	drv->shutdown(dev);
> +	if (ACPI_HANDLE(_dev))
> +		acpi_dev_pm_detach(_dev, true);
>  }
> 
>  /**