Re: [PATCH 0/3] Disable Suspend-to-Idle in Hyper-V and Fix Hibernation Interruptions

Re: [PATCH 0/3] Disable Suspend-to-Idle in Hyper-V and Fix Hibernation Interruptions

[Srivatsa S. Bhat]

Hi Vennela,

[+linux-pm, Rafael, Pavel, Len]

Let's CC the linux-pm mailing list for discussions related to power
management features (such as suspend/resume and hibernation).

On Thu, Sep 12, 2024 at 02:27:47PM -0700, Erni Sri Satya Vennela wrote:
> It has been reported that Hyper-V VM users can unintentionally abort
> hibernation by mouse or keyboard movements. To address this issue,
> we have decided to remove the wakeup events for the Hyper-V keyboard
> and mouse driver.

From the description of the problem, it doesn't occur to me that this
is specific to Hyper-V. I was wondering if VMs on other hypervisor
platforms wouldn't face the same issue? I'd like to recommend
exploring how this problem has been solved for other platforms, so
that we can reuse the same approach here. (If it turns out that
removing keyboard and mouse wakeup events is the way to go, then
great; otherwise, we can learn and apply the recommended solution).

> However, this change introduces another problem: 
> Suspend-to-Idle brings the system down with no method to wake it back up.
> 
> Given that there are no real users of Suspend-to-Idle in Hyper-V,
> we have decided to disable this feature for VMBus. This results in:
> 
> $echo freeze > /sys/power/state
> > bash: echo: write error: Operation not supported
> 
> The keyboard and mouse were previously registered as wakeup sources to
> interrupt the freeze operation in a VM. Since the freeze operation itself
> is no longer supported, we are disabling them as wakeup events.
> 
> This patchset ensures that the system remains stable and prevents
> unintended interruptions during hibernation.
> 
> Erni Sri Satya Vennela (3):
>   Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus
>   Revert "Input: hyperv-keyboard - register as a wakeup source"
>   Revert "HID: hyperv: register as a wakeup source"
> 
>  drivers/hid/hid-hyperv.c              |  6 ------
>  drivers/hv/vmbus_drv.c                | 15 ++++++++++++++-
>  drivers/input/serio/hyperv-keyboard.c | 12 ------------
>  3 files changed, 14 insertions(+), 19 deletions(-)
> 
> -- 
> 2.34.1
> 
> 

Regards,
Srivatsa
Microsoft Linux Systems Group

Re: [PATCH 1/3] Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus

[Srivatsa S. Bhat]

[+linux-pm, Rafael, Len, Pavel]

On Thu, Sep 12, 2024 at 02:27:48PM -0700, Erni Sri Satya Vennela wrote:
> If the Virtual Machine Connection window is focused,
> a Hyper-V VM user can unintentionally touch the keyboard/mouse
> when the VM is hibernating or resuming, and consequently the
> hibernation or resume operation can be aborted unexpectedly.
> Fix the issue by no longer registering the keyboard/mouse as
> wakeup devices (see the other two patches for the
> changes to drivers/input/serio/hyperv-keyboard.c and
> drivers/hid/hid-hyperv.c).
> 
> The keyboard/mouse were registered as wakeup devices because the
> VM needs to be woken up from the Suspend-to-Idle state after
> a user runs "echo freeze > /sys/power/state". It seems like
> the Suspend-to-Idle feature has no real users in practice, so
> let's no longer support that by returning -EOPNOTSUPP if a
> user tries to use that.
> 
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> ---
>  drivers/hv/vmbus_drv.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 965d2a4efb7e..4efd8856392f 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -900,6 +900,19 @@ static void vmbus_shutdown(struct device *child_device)
>  }
>  
>  #ifdef CONFIG_PM_SLEEP
> +/*
> + * vmbus_freeze - Suspend-to-Idle
> + */
> +static int vmbus_freeze(struct device *child_device)
> +{
> +/*
> + * Do not support Suspend-to-Idle ("echo freeze > /sys/power/state") as
> + * that would require registering the Hyper-V synthetic mouse/keyboard
> + * devices as wakeup devices, which can abort hibernation/resume unexpectedly.
> + */
> +	return -EOPNOTSUPP;
> +}
> +
>  /*
>   * vmbus_suspend - Suspend a vmbus device
>   */
> @@ -969,7 +982,7 @@ static void vmbus_device_release(struct device *device)
>   */
>  
>  static const struct dev_pm_ops vmbus_pm = {
> -	.suspend_noirq	= NULL,
> +	.suspend_noirq  = vmbus_freeze,
>  	.resume_noirq	= NULL,
>  	.freeze_noirq	= vmbus_suspend,
>  	.thaw_noirq	= vmbus_resume,
> -- 
> 2.34.1
> 
> 

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Srivatsa S. Bhat]

[+linux-pm, Rafael, Len, Pavel]

On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> 
> Remove keyboard as wakeup source since Suspend-to-Idle feature
> is disabled.
> 
> Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> ---
>  drivers/input/serio/hyperv-keyboard.c | 12 ------------
>  1 file changed, 12 deletions(-)
> 
> diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> index 31d9dacd2fd1..b42c546636bf 100644
> --- a/drivers/input/serio/hyperv-keyboard.c
> +++ b/drivers/input/serio/hyperv-keyboard.c
> @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
>  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
>  		}
>  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> -
> -		/*
> -		 * Only trigger a wakeup on key down, otherwise
> -		 * "echo freeze > /sys/power/state" can't really enter the
> -		 * state because the Enter-UP can trigger a wakeup at once.
> -		 */
> -		if (!(info & IS_BREAK))
> -			pm_wakeup_hard_event(&hv_dev->device);
> -
>  		break;
>  
>  	default:
> @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
>  		goto err_close_vmbus;
>  
>  	serio_register_port(kbd_dev->hv_serio);
> -
> -	device_init_wakeup(&hv_dev->device, true);
> -
>  	return 0;
>  
>  err_close_vmbus:
> -- 
> 2.34.1
> 
> 

Re: [PATCH 3/3] Revert "HID: hyperv: register as a wakeup source"

[Srivatsa S. Bhat]

[+linux-pm, Rafael, Len, Pavel]

On Thu, Sep 12, 2024 at 02:27:50PM -0700, Erni Sri Satya Vennela wrote:
> This reverts commit f1210455e78a610c7b316389b31c162c371d888c.
> 
> Remove mouse as wakeup source since Suspend-to-Idle feature
> is disabled.
> 
> Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> ---
>  drivers/hid/hid-hyperv.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> index f33485d83d24..b6d0f7db4c93 100644
> --- a/drivers/hid/hid-hyperv.c
> +++ b/drivers/hid/hid-hyperv.c
> @@ -293,9 +293,6 @@ static void mousevsc_on_receive(struct hv_device *device,
>  		memcpy(input_dev->input_buf, input_report->buffer, len);
>  		hid_input_report(input_dev->hid_device, HID_INPUT_REPORT,
>  				 input_dev->input_buf, len, 1);
> -
> -		pm_wakeup_hard_event(&input_dev->device->device);
> -
>  		break;
>  	default:
>  		pr_err("unsupported hid msg type - type %d len %d\n",
> @@ -502,8 +499,6 @@ static int mousevsc_probe(struct hv_device *device,
>  		goto probe_err2;
>  	}
>  
> -	device_init_wakeup(&device->device, true);
> -
>  	input_dev->connected = true;
>  	input_dev->init_complete = true;
>  
> @@ -526,7 +521,6 @@ static void mousevsc_remove(struct hv_device *dev)
>  {
>  	struct mousevsc_dev *input_dev = hv_get_drvdata(dev);
>  
> -	device_init_wakeup(&dev->device, false);
>  	vmbus_close(dev->channel);
>  	hid_hw_stop(input_dev->hid_device);
>  	hid_destroy_device(input_dev->hid_device);
> -- 
> 2.34.1
> 
> 

Re: [PATCH 0/3] Disable Suspend-to-Idle in Hyper-V and Fix Hibernation Interruptions

[Erni Sri Satya Vennela]

On Tue, Sep 24, 2024 at 03:26:14AM +0000, Srivatsa S. Bhat wrote:
> Hi Vennela,
> 
> [+linux-pm, Rafael, Pavel, Len]
> 
> Let's CC the linux-pm mailing list for discussions related to power
> management features (such as suspend/resume and hibernation).
> 
> On Thu, Sep 12, 2024 at 02:27:47PM -0700, Erni Sri Satya Vennela wrote:
> > It has been reported that Hyper-V VM users can unintentionally abort
> > hibernation by mouse or keyboard movements. To address this issue,
> > we have decided to remove the wakeup events for the Hyper-V keyboard
> > and mouse driver.
> 
> >From the description of the problem, it doesn't occur to me that this
> is specific to Hyper-V. I was wondering if VMs on other hypervisor
> platforms wouldn't face the same issue? I'd like to recommend
> exploring how this problem has been solved for other platforms, so
> that we can reuse the same approach here. (If it turns out that
> removing keyboard and mouse wakeup events is the way to go, then
> great; otherwise, we can learn and apply the recommended solution).
> 
This is how the keyboard and mouse devices can be disabled manually and
is the proper way to address this issue.
>echo disabled > /sys/bus/vmbus/drivers/hid_hyperv/$HV_MOUSE/power/wakeup
>echo disabled > 
>/sys/bus/vmbus/drivers/hyperv_keyboard/$HV_KEYBOARD/power/wakeup
>systemctl hibernate
But based on customer feedback we are totally eliminating them as wakeup
events.

Initially, they were registered as wakeup events to wakeup from
Suspend-to-Idle state. Since there is no real user of this operation,
we are disabling them to ensure they do not interfere with hibernation
process.
> > However, this change introduces another problem: 
> > Suspend-to-Idle brings the system down with no method to wake it back up.
> > 
> > Given that there are no real users of Suspend-to-Idle in Hyper-V,
> > we have decided to disable this feature for VMBus. This results in:
> > 
> > $echo freeze > /sys/power/state
> > > bash: echo: write error: Operation not supported
> > 
> > The keyboard and mouse were previously registered as wakeup sources to
> > interrupt the freeze operation in a VM. Since the freeze operation itself
> > is no longer supported, we are disabling them as wakeup events.
> > 
> > This patchset ensures that the system remains stable and prevents
> > unintended interruptions during hibernation.
> > 
> > Erni Sri Satya Vennela (3):
> >   Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus
> >   Revert "Input: hyperv-keyboard - register as a wakeup source"
> >   Revert "HID: hyperv: register as a wakeup source"
> > 
> >  drivers/hid/hid-hyperv.c              |  6 ------
> >  drivers/hv/vmbus_drv.c                | 15 ++++++++++++++-
> >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> >  3 files changed, 14 insertions(+), 19 deletions(-)
> > 
> > -- 
> > 2.34.1
> > 
> > 
> 
> Regards,
> Srivatsa
> Microsoft Linux Systems Group

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Dmitry Torokhov]

On Tue, Sep 24, 2024 at 03:28:51AM +0000, Srivatsa S. Bhat wrote:
> [+linux-pm, Rafael, Len, Pavel]
> 
> On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> > This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> > 
> > Remove keyboard as wakeup source since Suspend-to-Idle feature
> > is disabled.
> > 
> > Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> > ---
> >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> >  1 file changed, 12 deletions(-)
> > 
> > diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> > index 31d9dacd2fd1..b42c546636bf 100644
> > --- a/drivers/input/serio/hyperv-keyboard.c
> > +++ b/drivers/input/serio/hyperv-keyboard.c
> > @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
> >  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
> >  		}
> >  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> > -
> > -		/*
> > -		 * Only trigger a wakeup on key down, otherwise
> > -		 * "echo freeze > /sys/power/state" can't really enter the
> > -		 * state because the Enter-UP can trigger a wakeup at once.
> > -		 */
> > -		if (!(info & IS_BREAK))
> > -			pm_wakeup_hard_event(&hv_dev->device);
> > -
> >  		break;
> >  
> >  	default:
> > @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
> >  		goto err_close_vmbus;
> >  
> >  	serio_register_port(kbd_dev->hv_serio);
> > -
> > -	device_init_wakeup(&hv_dev->device, true);

If you do not want the keyboard to be a wakeup source by default maybe
change this to:

	device_set_wakeup_capable(&hv_dev->device, true);

and leave the rest of the driver alone?

Same for the HID change.

Thanks.

-- 
Dmitry

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Erni Sri Satya Vennela]

On Fri, Oct 04, 2024 at 01:14:10AM -0700, Dmitry Torokhov wrote:
> On Tue, Sep 24, 2024 at 03:28:51AM +0000, Srivatsa S. Bhat wrote:
> > [+linux-pm, Rafael, Len, Pavel]
> > 
> > On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> > > This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> > > 
> > > Remove keyboard as wakeup source since Suspend-to-Idle feature
> > > is disabled.
> > > 
> > > Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> > > ---
> > >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> > >  1 file changed, 12 deletions(-)
> > > 
> > > diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> > > index 31d9dacd2fd1..b42c546636bf 100644
> > > --- a/drivers/input/serio/hyperv-keyboard.c
> > > +++ b/drivers/input/serio/hyperv-keyboard.c
> > > @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
> > >  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
> > >  		}
> > >  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> > > -
> > > -		/*
> > > -		 * Only trigger a wakeup on key down, otherwise
> > > -		 * "echo freeze > /sys/power/state" can't really enter the
> > > -		 * state because the Enter-UP can trigger a wakeup at once.
> > > -		 */
> > > -		if (!(info & IS_BREAK))
> > > -			pm_wakeup_hard_event(&hv_dev->device);
> > > -
> > >  		break;
> > >  
> > >  	default:
> > > @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
> > >  		goto err_close_vmbus;
> > >  
> > >  	serio_register_port(kbd_dev->hv_serio);
> > > -
> > > -	device_init_wakeup(&hv_dev->device, true);
> 
> If you do not want the keyboard to be a wakeup source by default maybe
> change this to:
> 
> 	device_set_wakeup_capable(&hv_dev->device, true);
> 
> and leave the rest of the driver alone?
> 
> Same for the HID change.
> 
> Thanks.
>
device_set_wakeup_capable() sets the @dev's power.can_wakeup flag and
adds wakeup-related attributes in sysfs.

Could you please help me understand why explicitly calling this function 
can be helpful in our use case?

> -- 
> Dmitry

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Erni Sri Satya Vennela]

On Thu, Oct 17, 2024 at 06:44:38AM -0700, Erni Sri Satya Vennela wrote:
> On Fri, Oct 04, 2024 at 01:14:10AM -0700, Dmitry Torokhov wrote:
> > On Tue, Sep 24, 2024 at 03:28:51AM +0000, Srivatsa S. Bhat wrote:
> > > [+linux-pm, Rafael, Len, Pavel]
> > > 
> > > On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> > > > This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> > > > 
> > > > Remove keyboard as wakeup source since Suspend-to-Idle feature
> > > > is disabled.
> > > > 
> > > > Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> > > > ---
> > > >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> > > >  1 file changed, 12 deletions(-)
> > > > 
> > > > diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> > > > index 31d9dacd2fd1..b42c546636bf 100644
> > > > --- a/drivers/input/serio/hyperv-keyboard.c
> > > > +++ b/drivers/input/serio/hyperv-keyboard.c
> > > > @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
> > > >  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
> > > >  		}
> > > >  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> > > > -
> > > > -		/*
> > > > -		 * Only trigger a wakeup on key down, otherwise
> > > > -		 * "echo freeze > /sys/power/state" can't really enter the
> > > > -		 * state because the Enter-UP can trigger a wakeup at once.
> > > > -		 */
> > > > -		if (!(info & IS_BREAK))
> > > > -			pm_wakeup_hard_event(&hv_dev->device);
> > > > -
> > > >  		break;
> > > >  
> > > >  	default:
> > > > @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
> > > >  		goto err_close_vmbus;
> > > >  
> > > >  	serio_register_port(kbd_dev->hv_serio);
> > > > -
> > > > -	device_init_wakeup(&hv_dev->device, true);
> > 
> > If you do not want the keyboard to be a wakeup source by default maybe
> > change this to:
> > 
> > 	device_set_wakeup_capable(&hv_dev->device, true);
> > 
> > and leave the rest of the driver alone?
> > 
> > Same for the HID change.
> > 
> > Thanks.
> >
> device_set_wakeup_capable() sets the @dev's power.can_wakeup flag and
> adds wakeup-related attributes in sysfs.
> 
> Could you please help me understand why explicitly calling this function 
> can be helpful in our use case?
> 
> > -- 
> > Dmitry
Just following up on this patch. Could you please help me understand the
reason for the change?

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Saurabh Singh Sengar]

On Fri, Nov 08, 2024 at 02:47:41AM -0800, Erni Sri Satya Vennela wrote:
> On Thu, Oct 17, 2024 at 06:44:38AM -0700, Erni Sri Satya Vennela wrote:
> > On Fri, Oct 04, 2024 at 01:14:10AM -0700, Dmitry Torokhov wrote:
> > > On Tue, Sep 24, 2024 at 03:28:51AM +0000, Srivatsa S. Bhat wrote:
> > > > [+linux-pm, Rafael, Len, Pavel]
> > > > 
> > > > On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> > > > > This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> > > > > 
> > > > > Remove keyboard as wakeup source since Suspend-to-Idle feature
> > > > > is disabled.
> > > > > 
> > > > > Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> > > > > ---
> > > > >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> > > > >  1 file changed, 12 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> > > > > index 31d9dacd2fd1..b42c546636bf 100644
> > > > > --- a/drivers/input/serio/hyperv-keyboard.c
> > > > > +++ b/drivers/input/serio/hyperv-keyboard.c
> > > > > @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
> > > > >  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
> > > > >  		}
> > > > >  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> > > > > -
> > > > > -		/*
> > > > > -		 * Only trigger a wakeup on key down, otherwise
> > > > > -		 * "echo freeze > /sys/power/state" can't really enter the
> > > > > -		 * state because the Enter-UP can trigger a wakeup at once.
> > > > > -		 */
> > > > > -		if (!(info & IS_BREAK))
> > > > > -			pm_wakeup_hard_event(&hv_dev->device);
> > > > > -
> > > > >  		break;
> > > > >  
> > > > >  	default:
> > > > > @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
> > > > >  		goto err_close_vmbus;
> > > > >  
> > > > >  	serio_register_port(kbd_dev->hv_serio);
> > > > > -
> > > > > -	device_init_wakeup(&hv_dev->device, true);
> > > 
> > > If you do not want the keyboard to be a wakeup source by default maybe
> > > change this to:
> > > 
> > > 	device_set_wakeup_capable(&hv_dev->device, true);
> > > 
> > > and leave the rest of the driver alone?
> > > 
> > > Same for the HID change.
> > > 
> > > Thanks.
> > >
> > device_set_wakeup_capable() sets the @dev's power.can_wakeup flag and
> > adds wakeup-related attributes in sysfs.
> > 
> > Could you please help me understand why explicitly calling this function 
> > can be helpful in our use case?
> > 
> > > -- 
> > > Dmitry
> Just following up on this patch. Could you please help me understand the
> reason for the change?


Vennela,

There is a difference between "wakeup source registration" and "wakeup capable".
For this there are two flags defined in power management framework:
 1. power.wakeup
 2. power.can_wakeup
 
More details on these flags can be read here: 
https://www.kernel.org/doc/html/v6.12/driver-api/pm/devices.html

'device_init_wakeup(dev, true)' sets both; ie it registers the device as a wakeup
source and marks it as wakeup capable too.

In our case, the device is "wakeup capable" but we do not want to
"register it as a wakeup source". 'device_set_wakeup_capable(dev, true)' is more
appropriate because this marks the device as wakeup capable but doesn't register
it as a wakeup source knowingly.

I understand that Dimitry suggests not to revert the entire patch but to replace
'device_init_wakeup' with 'device_set_wakeup_capable', to mark the device as
capable of wakeup but knowingly skipping the registering part.

Requesting Dimitry to correct me if there is any misinterpretation.

While fixing this in next version, please fix the kernel bot warings as well
reported for 1/3 patch of this series.

- Saurabh

Re: [PATCH 2/3] Revert "Input: hyperv-keyboard - register as a wakeup source"

[Erni Sri Satya Vennela]

On Mon, Dec 09, 2024 at 09:16:23AM -0800, Saurabh Singh Sengar wrote:
> On Fri, Nov 08, 2024 at 02:47:41AM -0800, Erni Sri Satya Vennela wrote:
> > On Thu, Oct 17, 2024 at 06:44:38AM -0700, Erni Sri Satya Vennela wrote:
> > > On Fri, Oct 04, 2024 at 01:14:10AM -0700, Dmitry Torokhov wrote:
> > > > On Tue, Sep 24, 2024 at 03:28:51AM +0000, Srivatsa S. Bhat wrote:
> > > > > [+linux-pm, Rafael, Len, Pavel]
> > > > > 
> > > > > On Thu, Sep 12, 2024 at 02:27:49PM -0700, Erni Sri Satya Vennela wrote:
> > > > > > This reverts commit 62238f3aadc9bc56da70100e19ec61b9f8d72a5f.
> > > > > > 
> > > > > > Remove keyboard as wakeup source since Suspend-to-Idle feature
> > > > > > is disabled.
> > > > > > 
> > > > > > Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
> > > > > > ---
> > > > > >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> > > > > >  1 file changed, 12 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/input/serio/hyperv-keyboard.c b/drivers/input/serio/hyperv-keyboard.c
> > > > > > index 31d9dacd2fd1..b42c546636bf 100644
> > > > > > --- a/drivers/input/serio/hyperv-keyboard.c
> > > > > > +++ b/drivers/input/serio/hyperv-keyboard.c
> > > > > > @@ -162,15 +162,6 @@ static void hv_kbd_on_receive(struct hv_device *hv_dev,
> > > > > >  			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
> > > > > >  		}
> > > > > >  		spin_unlock_irqrestore(&kbd_dev->lock, flags);
> > > > > > -
> > > > > > -		/*
> > > > > > -		 * Only trigger a wakeup on key down, otherwise
> > > > > > -		 * "echo freeze > /sys/power/state" can't really enter the
> > > > > > -		 * state because the Enter-UP can trigger a wakeup at once.
> > > > > > -		 */
> > > > > > -		if (!(info & IS_BREAK))
> > > > > > -			pm_wakeup_hard_event(&hv_dev->device);
> > > > > > -
> > > > > >  		break;
> > > > > >  
> > > > > >  	default:
> > > > > > @@ -356,9 +347,6 @@ static int hv_kbd_probe(struct hv_device *hv_dev,
> > > > > >  		goto err_close_vmbus;
> > > > > >  
> > > > > >  	serio_register_port(kbd_dev->hv_serio);
> > > > > > -
> > > > > > -	device_init_wakeup(&hv_dev->device, true);
> > > > 
> > > > If you do not want the keyboard to be a wakeup source by default maybe
> > > > change this to:
> > > > 
> > > > 	device_set_wakeup_capable(&hv_dev->device, true);
> > > > 
> > > > and leave the rest of the driver alone?
> > > > 
> > > > Same for the HID change.
> > > > 
> > > > Thanks.
> > > >
> > > device_set_wakeup_capable() sets the @dev's power.can_wakeup flag and
> > > adds wakeup-related attributes in sysfs.
> > > 
> > > Could you please help me understand why explicitly calling this function 
> > > can be helpful in our use case?
> > > 
> > > > -- 
> > > > Dmitry
> > Just following up on this patch. Could you please help me understand the
> > reason for the change?
> 
> 
> Vennela,
> 
> There is a difference between "wakeup source registration" and "wakeup capable".
> For this there are two flags defined in power management framework:
>  1. power.wakeup
>  2. power.can_wakeup
>  
> More details on these flags can be read here: 
> https://www.kernel.org/doc/html/v6.12/driver-api/pm/devices.html
> 
> 'device_init_wakeup(dev, true)' sets both; ie it registers the device as a wakeup
> source and marks it as wakeup capable too.
> 
> In our case, the device is "wakeup capable" but we do not want to
> "register it as a wakeup source". 'device_set_wakeup_capable(dev, true)' is more
> appropriate because this marks the device as wakeup capable but doesn't register
> it as a wakeup source knowingly.
> 
> I understand that Dimitry suggests not to revert the entire patch but to replace
> 'device_init_wakeup' with 'device_set_wakeup_capable', to mark the device as
> capable of wakeup but knowingly skipping the registering part.
> 
> Requesting Dimitry to correct me if there is any misinterpretation.
> 
> While fixing this in next version, please fix the kernel bot warings as well
> reported for 1/3 patch of this series.
> 
> - Saurabh
Thanks for the clarification Saurabh.
I'll be incorporating these changes in the next verison of the patch.

- Vennela