Re: [PATCH] PCI: PM: Also move to D0 before calling pci_legacy_resume_early()

From: Bjorn Helgaas <helgaas@kernel.org>
To: Dexuan Cui <decui@microsoft.com>
Cc: "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Michael Kelley <mikelley@microsoft.com>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"driverdev-devel@linuxdriverproject.org" 
	<driverdev-devel@linuxdriverproject.org>,
	Sasha Levin <Alexander.Levin@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	KY Srinivasan <kys@microsoft.com>,
	"olaf@aepfle.de" <olaf@aepfle.de>,
	"apw@canonical.com" <apw@canonical.com>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	vkuznets <vkuznets@redhat.com>,
	"marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"jackm@mellanox.com" <jackm@mellanox.com>
Subject: Re: [PATCH] PCI: PM: Also move to D0 before calling pci_legacy_resume_early()
Date: Thu, 8 Aug 2019 14:19:13 -0500	[thread overview]
Message-ID: <20190808191913.GI151852@google.com> (raw)
In-Reply-To: <PU1P153MB01695867B01987A8C239A8CCBFD70@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM>

On Thu, Aug 08, 2019 at 06:46:51PM +0000, Dexuan Cui wrote:
> 
> In pci_legacy_suspend_late(), the device state is moved to PCI_UNKNOWN.
> In pci_pm_thaw_noirq(), the state is supposed to be moved back to PCI_D0,
> but the current code misses the pci_legacy_resume_early() path, so the
> state remains in PCI_UNKNOWN in that path, and during hiberantion this
> causes an error for the Mellanox VF driver, which fails to enable
> MSI-X: pci_msi_supported() is false due to dev->current_state != PCI_D0:

s/hiberantion/hibernation/

Actually, it sounds more like "during *resume*, this causes an error",
so maybe you want s/hiberantion/resume/ instead?

> mlx4_core a6d1:00:02.0: Detected virtual function - running in slave mode
> mlx4_core a6d1:00:02.0: Sending reset
> mlx4_core a6d1:00:02.0: Sending vhcr0
> mlx4_core a6d1:00:02.0: HCA minimum page size:512
> mlx4_core a6d1:00:02.0: Timestamping is not supported in slave mode
> mlx4_core a6d1:00:02.0: INTx is not supported in multi-function mode, aborting
> PM: dpm_run_callback(): pci_pm_thaw+0x0/0xd7 returns -95
> PM: Device a6d1:00:02.0 failed to thaw: error -95
> 
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>  drivers/pci/pci-driver.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 36dbe960306b..27dfc68db9e7 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1074,15 +1074,16 @@ static int pci_pm_thaw_noirq(struct device *dev)
>  			return error;
>  	}
>  
> -	if (pci_has_legacy_pm_support(pci_dev))
> -		return pci_legacy_resume_early(dev);
> -
>  	/*
>  	 * pci_restore_state() requires the device to be in D0 (because of MSI
>  	 * restoration among other things), so force it into D0 in case the
>  	 * driver's "freeze" callbacks put it into a low-power state directly.
>  	 */
>  	pci_set_power_state(pci_dev, PCI_D0);
> +
> +	if (pci_has_legacy_pm_support(pci_dev))
> +		return pci_legacy_resume_early(dev);
> +
>  	pci_restore_state(pci_dev);
>  
>  	if (drv && drv->pm && drv->pm->thaw_noirq)
> -- 
> 2.19.1
> 