Re: [RFD][PATCH 7/7] PM / ACPI: Take device PM QoS flags into account

[Huang Ying <ying.huang@intel.com>]

On Fri, 2012-09-28 at 23:56 +0200, Rafael J. Wysocki wrote:
> Make ACPI power management routines and PCI power management
> routines depending on ACPI take device PM QoS flags into account
> when deciding what power state to put the device into.
> 
> In particular, after this change acpi_pm_device_sleep_state() will
> not return ACPI_STATE_D3_COLD as the deepest available low-power
> state if PM_QOS_FLAG_NO_POWER_OFF is requested for the device and it
> will not require remote wakeup to work for the device in the returned
> low-power state if there is at least one PM QoS flags request for the
> device, but PM_QOS_FLAG_REMOTE_WAKEUP is not requested for it.
> 
> Accordingly, acpi_pci_set_power_state() will refuse to put the
> device into D3cold if PM_QOS_FLAG_NO_POWER_OFF is requested for it.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>  drivers/acpi/sleep.c   |   16 ++++++++++++----
>  drivers/pci/pci-acpi.c |    8 +++++++-
>  2 files changed, 19 insertions(+), 5 deletions(-)
> 
> Index: linux/drivers/pci/pci-acpi.c
> ===================================================================
> --- linux.orig/drivers/pci/pci-acpi.c
> +++ linux/drivers/pci/pci-acpi.c
> @@ -17,6 +17,7 @@
>  
>  #include <linux/pci-acpi.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/pm_qos.h>
>  #include "pci.h"
>  
>  static DEFINE_MUTEX(pci_acpi_pm_notify_mtx);
> @@ -257,11 +258,16 @@ static int acpi_pci_set_power_state(stru
>  		return -ENODEV;
>  
>  	switch (state) {
> +	case PCI_D3cold:
> +		if (dev_pm_qos_flags(&dev->dev, PM_QOS_FLAG_NO_POWER_OFF) ==
> +				PM_QOS_FLAGS_ALL) {
> +			error = -EBUSY;
> +			break;
> +		}
>  	case PCI_D0:
>  	case PCI_D1:
>  	case PCI_D2:
>  	case PCI_D3hot:
> -	case PCI_D3cold:
>  		error = acpi_bus_set_power(handle, state_conv[state]);
>  	}
>  
> Index: linux/drivers/acpi/sleep.c
> ===================================================================
> --- linux.orig/drivers/acpi/sleep.c
> +++ linux/drivers/acpi/sleep.c
> @@ -19,6 +19,7 @@
>  #include <linux/acpi.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/pm_qos.h>
>  
>  #include <asm/io.h>
>  
> @@ -711,6 +712,7 @@ int acpi_pm_device_sleep_state(struct de
>  	struct acpi_device *adev;
>  	char acpi_method[] = "_SxD";
>  	unsigned long long d_min, d_max;
> +	bool wakeup = false;
>  
>  	if (d_max_in < ACPI_STATE_D0 || d_max_in > ACPI_STATE_D3)
>  		return -EINVAL;
> @@ -718,6 +720,8 @@ int acpi_pm_device_sleep_state(struct de
>  		printk(KERN_DEBUG "ACPI handle has no context!\n");
>  		return -ENODEV;
>  	}
> +	if (dev_pm_qos_flags(dev, PM_QOS_FLAG_NO_POWER_OFF) == PM_QOS_FLAGS_ALL)
> +		d_max_in = ACPI_STATE_D3_HOT;

In theory, d_max_in may < ACPI_STATE_D3_HOT.  So better to be

d_max_in = min_t(int, d_max_in, ACPI_STATE_D3_HOT);

But in fact, d_max_in is introduced to support something similar to
PM_QOS_FLAG_NO_POWER_OFF, so I think we can remove d_max_in in the
future.

Best Regards,
Huang Ying

>  
>  	acpi_method[2] = '0' + acpi_target_sleep_state;
>  	/*
> @@ -737,8 +741,14 @@ int acpi_pm_device_sleep_state(struct de
>  	 * NOTE: We rely on acpi_evaluate_integer() not clobbering the integer
>  	 * provided -- that's our fault recovery, we ignore retval.
>  	 */
> -	if (acpi_target_sleep_state > ACPI_STATE_S0)
> +	if (acpi_target_sleep_state > ACPI_STATE_S0) {
>  		acpi_evaluate_integer(handle, acpi_method, NULL, &d_min);
> +		wakeup = device_may_wakeup(dev) && adev->wakeup.flags.valid
> +			&& adev->wakeup.sleep_state >= acpi_target_sleep_state;
> +	} else if (dev_pm_qos_flags(dev, PM_QOS_FLAG_REMOTE_WAKEUP) !=
> +			PM_QOS_FLAGS_NONE) {
> +		wakeup = adev->wakeup.flags.valid;
> +	}
>  
>  	/*
>  	 * If _PRW says we can wake up the system from the target sleep state,
> @@ -747,9 +757,7 @@ int acpi_pm_device_sleep_state(struct de
>  	 * (ACPI 3.x), it should return the maximum (lowest power) D-state that
>  	 * can wake the system.  _S0W may be valid, too.
>  	 */
> -	if (acpi_target_sleep_state == ACPI_STATE_S0 ||
> -	    (device_may_wakeup(dev) && adev->wakeup.flags.valid &&
> -	     adev->wakeup.sleep_state >= acpi_target_sleep_state)) {
> +	if (wakeup) {
>  		acpi_status status;
>  
>  		acpi_method[3] = 'W';
>