From: Dexuan Cui <decui@microsoft.com>
To: "lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Cc: 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>,
Dexuan Cui <decui@microsoft.com>
Subject: [PATCH v2] PCI: PM: Move to D0 before calling pci_legacy_resume_early()
Date: Wed, 14 Aug 2019 01:06:55 +0000 [thread overview]
Message-ID: <KU1P153MB016637CAEAD346F0AA8E3801BFAD0@KU1P153MB0166.APCP153.PROD.OUTLOOK.COM> (raw)
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. As a result, in the resume
phase of hibernation, this causes an error for the Mellanox VF driver,
which fails to enable MSI-X because pci_msi_supported() is false due
to dev->current_state != PCI_D0:
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
To be more accurate, the "resume" phase means the "thaw" callbacks which
run before the system enters hibernation: when the user runs the command
"echo disk > /sys/power/state" for hibernation, first the kernel "freezes"
all the devices and creates a hibernation image, then the kernel "thaws"
the devices including the disk/NIC, writes the memory to the disk, and
powers down. This patch fixes the error message for the Mellanox VF driver
in this phase.
When the system starts again, a fresh kernel starts to run, and when the
kernel detects that a hibernation image was saved, the kernel "quiesces"
the devices, and then "restores" the devices from the saved image. In this
path:
device_resume_noirq() -> ... ->
pci_pm_restore_noirq() ->
pci_pm_default_resume_early() ->
pci_power_up() moves the device states back to PCI_D0. This path is
not broken and doesn't need my patch.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
changes in v2:
Updated the changelog with more details.
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
next reply other threads:[~2019-08-14 1:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 1:06 Dexuan Cui [this message]
2019-09-03 0:34 ` [PATCH v2] PCI: PM: Move to D0 before calling pci_legacy_resume_early() Dexuan Cui
2019-09-25 22:25 ` Dexuan Cui
2019-10-07 13:24 ` Bjorn Helgaas
2019-10-07 18:57 ` Dexuan Cui
2019-10-08 17:32 ` Rafael J. Wysocki
2019-10-08 19:56 ` Bjorn Helgaas
2019-10-09 0:16 ` Dexuan Cui
2019-10-10 16:45 ` Rafael J. Wysocki
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