linux-kernel - Re: [PATCH v4 1/2] PCI/PM: refactor pci_pm_suspend

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Message-ID: <cb94e592-0fd8-3274-aeeb-49fbd6f74761@intel.com>
Date:   Thu, 14 Apr 2022 19:53:25 +0200
From:   "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
To:     Rajvi Jingar <rajvi.jingar@...el.com>, <bhelgaas@...gle.com>
CC:     <david.e.box@...ux.intel.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] PCI/PM: refactor pci_pm_suspend_noirq()

On 3/25/2022 8:50 PM, Rajvi Jingar wrote:
> The state of the device is saved during pci_pm_suspend_noirq(), if it
> has not already been saved, regardless of the skip_bus_pm flag value. So
> skip_bus_pm check is removed before saving the device state.
>
> Signed-off-by: Rajvi Jingar <rajvi.jingar@...el.com>
> Suggested-by: David E. Box <david.e.box@...ux.intel.com>

Sorry for the delay here.

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>


> ---
>   v1 -> v2: add comments to the changes
>   v2 -> v3: move changelog after "---" marker
>   v3 -> v4: add "---" marker after changelog
> ---
>   drivers/pci/pci-driver.c | 18 ++++++------------
>   1 file changed, 6 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 4ceeb75fc899..8b55a90126a2 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -845,20 +845,14 @@ static int pci_pm_suspend_noirq(struct device *dev)
>   		}
>   	}
>   
> -	if (pci_dev->skip_bus_pm) {
> +	if (!pci_dev->state_saved) {
> +		pci_save_state(pci_dev);
>   		/*
> -		 * Either the device is a bridge with a child in D0 below it, or
> -		 * the function is running for the second time in a row without
> -		 * going through full resume, which is possible only during
> -		 * suspend-to-idle in a spurious wakeup case.  The device should
> -		 * be in D0 at this point, but if it is a bridge, it may be
> -		 * necessary to save its state.
> +		 * If the device is a bridge with a child in D0 below it, it needs to
> +		 * stay in D0, so check skip_bus_pm to avoid putting it into a
> +		 * low-power state in that case.
>   		 */
> -		if (!pci_dev->state_saved)
> -			pci_save_state(pci_dev);
> -	} else if (!pci_dev->state_saved) {
> -		pci_save_state(pci_dev);
> -		if (pci_power_manageable(pci_dev))
> +		if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
>   			pci_prepare_to_sleep(pci_dev);
>   	}
>