[char-misc-next] mei: me: allow runtime pm for platform with D0i3

[char-misc-next] mei: me: allow runtime pm for platform with D0i3

[Tomas Winkler]

>From the pci power documentation:
"The driver itself should not call pm_runtime_allow(), though. Instead,
it should let user space or some platform-specific code do that (user space
can do it via sysfs as stated above)..."

However, the S0ix residency cannot be reached without MEI device getting
into low power state. Hence, for mei devices that support D0i3, it's better
to make runtime power management mandatory and not rely on the system
integration such as udev rules.
This policy cannot be applied globally as some older platforms
were found to have broken power management.

Cc: <stable@vger.kernel.org> v4.13+
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Alexander Usyskin <alexander.usyskin@intel.com>
---
 drivers/misc/mei/pci-me.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/mei/pci-me.c b/drivers/misc/mei/pci-me.c
index f4f17552c9b8..4a0ccda4d04b 100644
--- a/drivers/misc/mei/pci-me.c
+++ b/drivers/misc/mei/pci-me.c
@@ -238,8 +238,11 @@ static int mei_me_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	 */
 	mei_me_set_pm_domain(dev);
 
-	if (mei_pg_is_enabled(dev))
+	if (mei_pg_is_enabled(dev)) {
 		pm_runtime_put_noidle(&pdev->dev);
+		if (hw->d0i3_supported)
+			pm_runtime_allow(&pdev->dev);
+	}
 
 	dev_dbg(&pdev->dev, "initialization successful.\n");
 
-- 
2.14.3

Re: [char-misc-next] mei: me: allow runtime pm for platform with D0i3

[Rafael J. Wysocki]

On 1/2/2018 11:01 AM, Tomas Winkler wrote:
>  From the pci power documentation:
> "The driver itself should not call pm_runtime_allow(), though. Instead,
> it should let user space or some platform-specific code do that (user space
> can do it via sysfs as stated above)..."
>
> However, the S0ix residency cannot be reached without MEI device getting
> into low power state. Hence, for mei devices that support D0i3, it's better
> to make runtime power management mandatory and not rely on the system
> integration such as udev rules.

It still is not mandatory with this change.  The default changes from 
"on" to "auto", but still user space can change it back to "on".

The change itself look OK, though.

> This policy cannot be applied globally as some older platforms
> were found to have broken power management.
>
> Cc: <stable@vger.kernel.org> v4.13+
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> Reviewed-by: Alexander Usyskin <alexander.usyskin@intel.com>
> ---
>   drivers/misc/mei/pci-me.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/mei/pci-me.c b/drivers/misc/mei/pci-me.c
> index f4f17552c9b8..4a0ccda4d04b 100644
> --- a/drivers/misc/mei/pci-me.c
> +++ b/drivers/misc/mei/pci-me.c
> @@ -238,8 +238,11 @@ static int mei_me_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>   	 */
>   	mei_me_set_pm_domain(dev);
>   
> -	if (mei_pg_is_enabled(dev))
> +	if (mei_pg_is_enabled(dev)) {
>   		pm_runtime_put_noidle(&pdev->dev);
> +		if (hw->d0i3_supported)
> +			pm_runtime_allow(&pdev->dev);
> +	}
>   
>   	dev_dbg(&pdev->dev, "initialization successful.\n");
>   

RE: [char-misc-next] mei: me: allow runtime pm for platform with D0i3

[Winkler, Tomas]

mei: me: allow runtime pm for platform with
> D0i3
> 
> On 1/2/2018 11:01 AM, Tomas Winkler wrote:
> >  From the pci power documentation:
> > "The driver itself should not call pm_runtime_allow(), though.
> > Instead, it should let user space or some platform-specific code do
> > that (user space can do it via sysfs as stated above)..."
> >
> > However, the S0ix residency cannot be reached without MEI device
> > getting into low power state. Hence, for mei devices that support
> > D0i3, it's better to make runtime power management mandatory and not
> > rely on the system integration such as udev rules.
> 
> It still is not mandatory with this change.  The default changes from "on" to
> "auto", but still user space can change it back to "on".
That's correct, maybe better statement would be  'default  setting' instead of 'mandatory'.
I can respin the patch if needed, let me know.  
> 
> The change itself look OK, though.

Thanks
Tomas 

Re: [char-misc-next] mei: me: allow runtime pm for platform with D0i3

[Rafael J. Wysocki]

On 1/4/2018 9:27 AM, Winkler, Tomas wrote:
> mei: me: allow runtime pm for platform with
>> D0i3
>>
>> On 1/2/2018 11:01 AM, Tomas Winkler wrote:
>>>   From the pci power documentation:
>>> "The driver itself should not call pm_runtime_allow(), though.
>>> Instead, it should let user space or some platform-specific code do
>>> that (user space can do it via sysfs as stated above)..."
>>>
>>> However, the S0ix residency cannot be reached without MEI device
>>> getting into low power state. Hence, for mei devices that support
>>> D0i3, it's better to make runtime power management mandatory and not
>>> rely on the system integration such as udev rules.
>> It still is not mandatory with this change.  The default changes from "on" to
>> "auto", but still user space can change it back to "on".
> That's correct, maybe better statement would be  'default  setting' instead of 'mandatory'.
> I can respin the patch if needed, let me know.

Greg has applied it already it seems, so I guess that shouldn't be 
necessary. :-)

Thanks,
Rafael