linux-kernel - Re: [PATCH v1] PCI: PM: Power up all devices during runtime resume

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Message-ID: <20220407154901.GA239301@bhelgaas>
Date:   Thu, 7 Apr 2022 10:49:01 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PCI <linux-pci@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v1] PCI: PM: Power up all devices during runtime resume

On Wed, Apr 06, 2022 at 09:00:52PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Currently, endpoint devices may not be powered up entirely during
> runtime resume that follows a D3hot -> D0 transition of the parent
> bridge.
> 
> Namely, even if the power state of an endpoint device, as indicated
> by its PCI_PM_CTRL register, is D0 after powering up its parent
> bridge, it may be still necessary to bring its ACPI companion into
> D0 and that should be done before accessing it.  However, the current
> code assumes that reading the PCI_PM_CTRL register is sufficient to
> establish the endpoint device's power state, which may lead to
> problems.
> 
> Address that by forcing a power-up of all PCI devices, including the
> platform firmware part of it, during runtime resume.
> 
> Link: https://lore.kernel.org/linux-pm/11967527.O9o76ZdvQC@kreacher
> Fixes: 5775b843a619 ("PCI: Restore config space on runtime resume despite being unbound")
> Reported-by: Abhishek Sahu <abhsahu@...dia.com>
> Tested-by: Abhishek Sahu <abhsahu@...dia.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Applied with Mika's reviewed-by to pci/pm for v5.19, thanks!

> ---
>  drivers/pci/pci-driver.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/pci/pci-driver.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci-driver.c
> +++ linux-pm/drivers/pci/pci-driver.c
> @@ -1312,7 +1312,7 @@ static int pci_pm_runtime_resume(struct
>  	 * to a driver because although we left it in D0, it may have gone to
>  	 * D3cold when the bridge above it runtime suspended.
>  	 */
> -	pci_restore_standard_config(pci_dev);
> +	pci_pm_default_resume_early(pci_dev);
>  
>  	if (!pci_dev->driver)
>  		return 0;
> 
> 
>