linux_dsm_epyc7002/drivers/pci
Rafael J. Wysocki d16749988d PCI: PM: Do not read power state in pci_enable_device_flags()
[ Upstream commit 4514d991d99211f225d83b7e640285f29f0755d0 ]

It should not be necessary to update the current_state field of
struct pci_dev in pci_enable_device_flags() before calling
do_pci_enable_device() for the device, because none of the
code between that point and the pci_set_power_state() call in
do_pci_enable_device() invoked later depends on it.

Moreover, doing that is actively harmful in some cases.  For example,
if the given PCI device depends on an ACPI power resource whose _STA
method initially returns 0 ("off"), but the config space of the PCI
device is accessible and the power state retrieved from the
PCI_PM_CTRL register is D0, the current_state field in the struct
pci_dev representing that device will get out of sync with the
power.state of its ACPI companion object and that will lead to
power management issues going forward.

To avoid such issues it is better to leave the current_state value
as is until it is changed to PCI_D0 by do_pci_enable_device() as
appropriate.  However, the power state of the device is not changed
to PCI_D0 if it is already enabled when pci_enable_device_flags()
gets called for it, so update its current_state in that case, but
use pci_update_current_state() covering platform PM too for that.

Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/
Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-11 14:47:18 +02:00
..
controller PCI: mediatek: Add missing of_node_put() to fix reference leak 2021-03-17 17:06:24 +01:00
endpoint
hotplug PCI: rpadlpar: Fix potential drc_name corruption in store functions 2021-03-25 09:04:16 +01:00
pcie PCI/LINK: Remove bandwidth notification 2021-03-17 17:06:24 +01:00
switch
access.c
ats.c
bus.c
ecam.c
host-bridge.c
iov.c
irq.c
Kconfig
Makefile
mmap.c
msi.c
of.c
p2pdma.c
pci-acpi.c PM: ACPI: PCI: Drop acpi_pm_set_bridge_wakeup() 2020-12-30 11:54:05 +01:00
pci-bridge-emul.c PCI: pci-bridge-emul: Fix array overruns, improve safety 2021-03-04 11:38:15 +01:00
pci-bridge-emul.h
pci-driver.c
pci-label.c
pci-mid.c
pci-pf-stub.c
pci-stub.c
pci-sysfs.c
pci.c PCI: PM: Do not read power state in pci_enable_device_flags() 2021-05-11 14:47:18 +02:00
pci.h
probe.c
proc.c
quirks.c PCI: Add function 1 DMA alias quirk for Marvell 9215 SATA controller 2021-03-11 14:17:26 +01:00
remove.c
rom.c
search.c
setup-bus.c
setup-irq.c
setup-res.c PCI: Decline to resize resources if boot config must be preserved 2021-03-04 11:37:18 +01:00
slot.c PCI: Fix pci_slot_release() NULL pointer dereference 2020-12-30 11:54:28 +01:00
syscall.c PCI: Align checking of syscall user config accessors 2021-03-04 11:38:12 +01:00
vc.c
vpd.c
xen-pcifront.c