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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/ABI/testing/sysfs-power
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
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+What: /sys/power/
+Date: August 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power directory will contain files that will
+ provide a unified interface to the power management
+ subsystem.
+
+What: /sys/power/state
+Date: November 2016
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/state file controls system sleep states.
+ Reading from this file returns the available sleep state
+ labels, which may be "mem" (suspend), "standby" (power-on
+ suspend), "freeze" (suspend-to-idle) and "disk" (hibernation).
+
+ Writing one of the above strings to this file causes the system
+ to transition into the corresponding state, if available.
+
+ See Documentation/admin-guide/pm/sleep-states.rst for more
+ information.
+
+What: /sys/power/mem_sleep
+Date: November 2016
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/mem_sleep file controls the operating mode of
+ system suspend. Reading from it returns the available modes
+ as "s2idle" (always present), "shallow" and "deep" (present if
+ supported). The mode that will be used on subsequent attempts
+ to suspend the system (by writing "mem" to the /sys/power/state
+ file described above) is enclosed in square brackets.
+
+ Writing one of the above strings to this file causes the mode
+ represented by it to be used on subsequent attempts to suspend
+ the system.
+
+ See Documentation/admin-guide/pm/sleep-states.rst for more
+ information.
+
+What: /sys/power/disk
+Date: September 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/disk file controls the operating mode of the
+ suspend-to-disk mechanism. Reading from this file returns
+ the name of the method by which the system will be put to
+ sleep on the next suspend. There are four methods supported:
+
+ 'firmware' - means that the memory image will be saved to disk
+ by some firmware, in which case we also assume that the
+ firmware will handle the system suspend.
+
+ 'platform' - the memory image will be saved by the kernel and
+ the system will be put to sleep by the platform driver (e.g.
+ ACPI or other PM registers).
+
+ 'shutdown' - the memory image will be saved by the kernel and
+ the system will be powered off.
+
+ 'reboot' - the memory image will be saved by the kernel and
+ the system will be rebooted.
+
+ Additionally, /sys/power/disk can be used to turn on one of the
+ two testing modes of the suspend-to-disk mechanism: 'testproc'
+ or 'test'. If the suspend-to-disk mechanism is in the
+ 'testproc' mode, writing 'disk' to /sys/power/state will cause
+ the kernel to disable nonboot CPUs and freeze tasks, wait for 5
+ seconds, unfreeze tasks and enable nonboot CPUs. If it is in
+ the 'test' mode, writing 'disk' to /sys/power/state will cause
+ the kernel to disable nonboot CPUs and freeze tasks, shrink
+ memory, suspend devices, wait for 5 seconds, resume devices,
+ unfreeze tasks and enable nonboot CPUs. Then, we are able to
+ look in the log messages and work out, for example, which code
+ is being slow and which device drivers are misbehaving.
+
+ The suspend-to-disk method may be chosen by writing to this
+ file one of the accepted strings:
+
+ - 'firmware'
+ - 'platform'
+ - 'shutdown'
+ - 'reboot'
+ - 'testproc'
+ - 'test'
+
+ It will only change to 'firmware' or 'platform' if the system
+ supports that.
+
+What: /sys/power/image_size
+Date: August 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/image_size file controls the size of the image
+ created by the suspend-to-disk mechanism. It can be written a
+ string representing a non-negative integer that will be used
+ as an upper limit of the image size, in bytes. The kernel's
+ suspend-to-disk code will do its best to ensure the image size
+ will not exceed this number. However, if it turns out to be
+ impossible, the kernel will try to suspend anyway using the
+ smallest image possible. In particular, if "0" is written to
+ this file, the suspend image will be as small as possible.
+
+ Reading from this file will display the current image size
+ limit, which is set to around 2/5 of available RAM by default.
+
+What: /sys/power/pm_trace
+Date: August 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/pm_trace file controls the code which saves the
+ last PM event point in the RTC across reboots, so that you can
+ debug a machine that just hangs during suspend (or more
+ commonly, during resume). Namely, the RTC is only used to save
+ the last PM event point if this file contains '1'. Initially
+ it contains '0' which may be changed to '1' by writing a
+ string representing a nonzero integer into it.
+
+ To use this debugging feature you should attempt to suspend
+ the machine, then reboot it and run::
+
+ dmesg -s 1000000 | grep 'hash matches'
+
+ If you do not get any matches (or they appear to be false
+ positives), it is possible that the last PM event point
+ referred to a device created by a loadable kernel module. In
+ this case cat /sys/power/pm_trace_dev_match (see below) after
+ your system is started up and the kernel modules are loaded.
+
+ CAUTION: Using it will cause your machine's real-time (CMOS)
+ clock to be set to a random invalid time after a resume.
+
+What; /sys/power/pm_trace_dev_match
+Date: October 2010
+Contact: James Hogan <jhogan@kernel.org>
+Description:
+ The /sys/power/pm_trace_dev_match file contains the name of the
+ device associated with the last PM event point saved in the RTC
+ across reboots when pm_trace has been used. More precisely it
+ contains the list of current devices (including those
+ registered by loadable kernel modules since boot) which match
+ the device hash in the RTC at boot, with a newline after each
+ one.
+
+ The advantage of this file over the hash matches printed to the
+ kernel log (see /sys/power/pm_trace), is that it includes
+ devices created after boot by loadable kernel modules.
+
+ Due to the small hash size necessary to fit in the RTC, it is
+ possible that more than one device matches the hash, in which
+ case further investigation is required to determine which
+ device is causing the problem. Note that genuine RTC clock
+ values (such as when pm_trace has not been used), can still
+ match a device and output its name here.
+
+What: /sys/power/pm_async
+Date: January 2009
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/pm_async file controls the switch allowing the
+ user space to enable or disable asynchronous suspend and resume
+ of devices. If enabled, this feature will cause some device
+ drivers' suspend and resume callbacks to be executed in parallel
+ with each other and with the main suspend thread. It is enabled
+ if this file contains "1", which is the default. It may be
+ disabled by writing "0" to this file, in which case all devices
+ will be suspended and resumed synchronously.
+
+What: /sys/power/wakeup_count
+Date: July 2010
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/wakeup_count file allows user space to put the
+ system into a sleep state while taking into account the
+ concurrent arrival of wakeup events. Reading from it returns
+ the current number of registered wakeup events and it blocks if
+ some wakeup events are being processed at the time the file is
+ read from. Writing to it will only succeed if the current
+ number of wakeup events is equal to the written value and, if
+ successful, will make the kernel abort a subsequent transition
+ to a sleep state if any wakeup events are reported after the
+ write has returned.
+
+What: /sys/power/reserved_size
+Date: May 2011
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/reserved_size file allows user space to control
+ the amount of memory reserved for allocations made by device
+ drivers during the "device freeze" stage of hibernation. It can
+ be written a string representing a non-negative integer that
+ will be used as the amount of memory to reserve for allocations
+ made by device drivers' "freeze" callbacks, in bytes.
+
+ Reading from this file will display the current value, which is
+ set to 1 MB by default.
+
+What: /sys/power/autosleep
+Date: April 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/autosleep file can be written one of the strings
+ returned by reads from /sys/power/state. If that happens, a
+ work item attempting to trigger a transition of the system to
+ the sleep state represented by that string is queued up. This
+ attempt will only succeed if there are no active wakeup sources
+ in the system at that time. After every execution, regardless
+ of whether or not the attempt to put the system to sleep has
+ succeeded, the work item requeues itself until user space
+ writes "off" to /sys/power/autosleep.
+
+ Reading from this file causes the last string successfully
+ written to it to be returned.
+
+What: /sys/power/wake_lock
+Date: February 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/wake_lock file allows user space to create
+ wakeup source objects and activate them on demand (if one of
+ those wakeup sources is active, reads from the
+ /sys/power/wakeup_count file block or return false). When a
+ string without white space is written to /sys/power/wake_lock,
+ it will be assumed to represent a wakeup source name. If there
+ is a wakeup source object with that name, it will be activated
+ (unless active already). Otherwise, a new wakeup source object
+ will be registered, assigned the given name and activated.
+ If a string written to /sys/power/wake_lock contains white
+ space, the part of the string preceding the white space will be
+ regarded as a wakeup source name and handled as descrived above.
+ The other part of the string will be regarded as a timeout (in
+ nanoseconds) such that the wakeup source will be automatically
+ deactivated after it has expired. The timeout, if present, is
+ set regardless of the current state of the wakeup source object
+ in question.
+
+ Reads from this file return a string consisting of the names of
+ wakeup sources created with the help of it that are active at
+ the moment, separated with spaces.
+
+
+What: /sys/power/wake_unlock
+Date: February 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/wake_unlock file allows user space to deactivate
+ wakeup sources created with the help of /sys/power/wake_lock.
+ When a string is written to /sys/power/wake_unlock, it will be
+ assumed to represent the name of a wakeup source to deactivate.
+
+ If a wakeup source object of that name exists and is active at
+ the moment, it will be deactivated.
+
+ Reads from this file return a string consisting of the names of
+ wakeup sources created with the help of /sys/power/wake_lock
+ that are inactive at the moment, separated with spaces.
+
+What: /sys/power/pm_print_times
+Date: May 2012
+Contact: Sameer Nanda <snanda@chromium.org>
+Description:
+ The /sys/power/pm_print_times file allows user space to
+ control whether the time taken by devices to suspend and
+ resume is printed. These prints are useful for hunting down
+ devices that take too long to suspend or resume.
+
+ Writing a "1" enables this printing while writing a "0"
+ disables it. The default value is "0". Reading from this file
+ will display the current value.
+
+What: /sys/power/pm_wakeup_irq
+Date: April 2015
+Contact: Alexandra Yates <alexandra.yates@linux.intel.org>
+Description:
+ The /sys/power/pm_wakeup_irq file reports to user space the IRQ
+ number of the first wakeup interrupt (that is, the first
+ interrupt from an IRQ line armed for system wakeup) seen by the
+ kernel during the most recent system suspend/resume cycle.
+
+ This output is useful for system wakeup diagnostics of spurious
+ wakeup interrupts.
+
+What: /sys/power/pm_debug_messages
+Date: July 2017
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/pm_debug_messages file controls the printing
+ of debug messages from the system suspend/hiberbation
+ infrastructure to the kernel log.
+
+ Writing a "1" to this file enables the debug messages and
+ writing a "0" (default) to it disables them. Reads from
+ this file return the current value.
+
+What: /sys/power/resume_offset
+Date: April 2018
+Contact: Mario Limonciello <mario.limonciello@outlook.com>
+Description:
+ This file is used for telling the kernel an offset into a disk
+ to use when hibernating the system such as with a swap file.
+
+ Reads from this file will display the current offset
+ the kernel will be using on the next hibernation
+ attempt.
+
+ Using this sysfs file will override any values that were
+ set using the kernel command line for disk offset.
+
+What: /sys/power/suspend_stats
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats directory contains suspend related
+ statistics.
+
+What: /sys/power/suspend_stats/success
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/success file contains the number
+ of times entering system sleep state succeeded.
+
+What: /sys/power/suspend_stats/fail
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/fail file contains the number
+ of times entering system sleep state failed.
+
+What: /sys/power/suspend_stats/failed_freeze
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_freeze file contains the
+ number of times freezing processes failed.
+
+What: /sys/power/suspend_stats/failed_prepare
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_prepare file contains the
+ number of times preparing all non-sysdev devices for
+ a system PM transition failed.
+
+What: /sys/power/suspend_stats/failed_resume
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_resume file contains the
+ number of times executing "resume" callbacks of
+ non-sysdev devices failed.
+
+What: /sys/power/suspend_stats/failed_resume_early
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_resume_early file contains
+ the number of times executing "early resume" callbacks
+ of devices failed.
+
+What: /sys/power/suspend_stats/failed_resume_noirq
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_resume_noirq file contains
+ the number of times executing "noirq resume" callbacks
+ of devices failed.
+
+What: /sys/power/suspend_stats/failed_suspend
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_suspend file contains
+ the number of times executing "suspend" callbacks
+ of all non-sysdev devices failed.
+
+What: /sys/power/suspend_stats/failed_suspend_late
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_suspend_late file contains
+ the number of times executing "late suspend" callbacks
+ of all devices failed.
+
+What: /sys/power/suspend_stats/failed_suspend_noirq
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/failed_suspend_noirq file contains
+ the number of times executing "noirq suspend" callbacks
+ of all devices failed.
+
+What: /sys/power/suspend_stats/last_failed_dev
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/last_failed_dev file contains
+ the last device for which a suspend/resume callback failed.
+
+What: /sys/power/suspend_stats/last_failed_errno
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/last_failed_errno file contains
+ the errno of the last failed attempt at entering
+ system sleep state.
+
+What: /sys/power/suspend_stats/last_failed_step
+Date: July 2019
+Contact: Kalesh Singh <kaleshsingh96@gmail.com>
+Description:
+ The /sys/power/suspend_stats/last_failed_step file contains
+ the last failed step in the suspend/resume path.
+
+What: /sys/power/sync_on_suspend
+Date: October 2019
+Contact: Jonas Meurer <jonas@freesources.org>
+Description:
+ This file controls whether or not the kernel will sync()
+ filesystems during system suspend (after freezing user space
+ and before suspending devices).
+
+ Writing a "1" to this file enables the sync() and writing a "0"
+ disables it. Reads from the file return the current value.
+ The default is "1" if the build-time "SUSPEND_SKIP_SYNC" config
+ flag is unset, or "0" otherwise.