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Filename Latest commit message Latest commit date
Rafael J. Wysocki 4eaefe8c62 nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled
One of the modifications made by commit d916b1be94 ("nvme-pci: use
host managed power state for suspend") was adding a pci_save_state()
call to nvme_suspend() so as to instruct the PCI bus type to leave
devices handled by the nvme driver in D0 during suspend-to-idle.
That was done with the assumption that ASPM would transition the
device's PCIe link into a low-power state when the device became
inactive.  However, if ASPM is disabled for the device, its PCIe
link will stay in L0 and in that case commit d916b1be94 is likely
to cause the energy used by the system while suspended to increase.

Namely, if the device in question works in accordance with the PCIe
specification, putting it into D3hot causes its PCIe link to go to
L1 or L2/L3 Ready, which is lower-power than L0.  Since the energy
used by the system while suspended depends on the state of its PCIe
link (as a general rule, the lower-power the state of the link, the
less energy the system will use), putting the device into D3hot
during suspend-to-idle should be more energy-efficient that leaving
it in D0 with disabled ASPM.

For this reason, avoid leaving NVMe devices with disabled ASPM in D0
during suspend-to-idle.  Instead, shut them down entirely and let
the PCI bus type put them into D3.

Fixes: d916b1be94 ("nvme-pci: use host managed power state for suspend")
Link: https://lore.kernel.org/linux-pm/2763495.NmdaWeg79L@kreacher/T/#t
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
2019-08-12 10:47:55 +02:00
arch RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
block block, bfq: handle NULL return value by bfq_init_rq() 2019-08-08 07:31:50 -06:00
certs
crypto
Documentation RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
drivers nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled 2019-08-12 10:47:55 +02:00
fs dax fixes v5.3-rc4 2019-08-11 13:15:10 -07:00
include PCI/ASPM: Add pcie_aspm_enabled() 2019-08-12 10:47:55 +02:00
init
ipc
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 15:48:02 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
LICENSES
mm mm/memremap: Fix reuse of pgmap instances with internal references 2019-08-09 14:16:15 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples
scripts kbuild: show hint if subdir-y/m is used to visit module Makefile 2019-08-10 01:45:31 +09:00
security
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 16:19:02 -07:00
usr
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Char/misc fixes for 5.3-rc4 2019-08-10 12:24:20 -07:00
Makefile Linux 5.3-rc4 2019-08-11 13:26:41 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.