From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 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(). ... --- Documentation/driver-api/media/v4l2-event.rst | 181 ++++++++++++++++++++++++++ 1 file changed, 181 insertions(+) create mode 100644 Documentation/driver-api/media/v4l2-event.rst (limited to 'Documentation/driver-api/media/v4l2-event.rst') diff --git a/Documentation/driver-api/media/v4l2-event.rst b/Documentation/driver-api/media/v4l2-event.rst new file mode 100644 index 000000000..52d4fbc5d --- /dev/null +++ b/Documentation/driver-api/media/v4l2-event.rst @@ -0,0 +1,181 @@ +.. SPDX-License-Identifier: GPL-2.0 + +V4L2 events +----------- + +The V4L2 events provide a generic way to pass events to user space. +The driver must use :c:type:`v4l2_fh` to be able to support V4L2 events. + +Events are subscribed per-filehandle. An event specification consists of a +``type`` and is optionally associated with an object identified through the +``id`` field. If unused, then the ``id`` is 0. So an event is uniquely +identified by the ``(type, id)`` tuple. + +The :c:type:`v4l2_fh` struct has a list of subscribed events on its +``subscribed`` field. + +When the user subscribes to an event, a :c:type:`v4l2_subscribed_event` +struct is added to :c:type:`v4l2_fh`\ ``.subscribed``, one for every +subscribed event. + +Each :c:type:`v4l2_subscribed_event` struct ends with a +:c:type:`v4l2_kevent` ringbuffer, with the size given by the caller +of :c:func:`v4l2_event_subscribe`. This ringbuffer is used to store any events +raised by the driver. + +So every ``(type, ID)`` event tuple will have its own +:c:type:`v4l2_kevent` ringbuffer. This guarantees that if a driver is +generating lots of events of one type in a short time, then that will +not overwrite events of another type. + +But if you get more events of one type than the size of the +:c:type:`v4l2_kevent` ringbuffer, then the oldest event will be dropped +and the new one added. + +The :c:type:`v4l2_kevent` struct links into the ``available`` +list of the :c:type:`v4l2_fh` struct so :ref:`VIDIOC_DQEVENT` will +know which event to dequeue first. + +Finally, if the event subscription is associated with a particular object +such as a V4L2 control, then that object needs to know about that as well +so that an event can be raised by that object. So the ``node`` field can +be used to link the :c:type:`v4l2_subscribed_event` struct into a list of +such objects. + +So to summarize: + +- struct v4l2_fh has two lists: one of the ``subscribed`` events, + and one of the ``available`` events. + +- struct v4l2_subscribed_event has a ringbuffer of raised + (pending) events of that particular type. + +- If struct v4l2_subscribed_event is associated with a specific + object, then that object will have an internal list of + struct v4l2_subscribed_event so it knows who subscribed an + event to that object. + +Furthermore, the internal struct v4l2_subscribed_event has +``merge()`` and ``replace()`` callbacks which drivers can set. These +callbacks are called when a new event is raised and there is no more room. + +The ``replace()`` callback allows you to replace the payload of the old event +with that of the new event, merging any relevant data from the old payload +into the new payload that replaces it. It is called when this event type has +a ringbuffer with size is one, i.e. only one event can be stored in the +ringbuffer. + +The ``merge()`` callback allows you to merge the oldest event payload into +that of the second-oldest event payload. It is called when +the ringbuffer has size is greater than one. + +This way no status information is lost, just the intermediate steps leading +up to that state. + +A good example of these ``replace``/``merge`` callbacks is in v4l2-event.c: +``ctrls_replace()`` and ``ctrls_merge()`` callbacks for the control event. + +.. note:: + these callbacks can be called from interrupt context, so they must + be fast. + +In order to queue events to video device, drivers should call: + + :c:func:`v4l2_event_queue ` + (:c:type:`vdev `, :c:type:`ev `) + +The driver's only responsibility is to fill in the type and the data fields. +The other fields will be filled in by V4L2. + +Event subscription +~~~~~~~~~~~~~~~~~~ + +Subscribing to an event is via: + + :c:func:`v4l2_event_subscribe ` + (:c:type:`fh `, :c:type:`sub ` , + elems, :c:type:`ops `) + + +This function is used to implement :c:type:`video_device`-> +:c:type:`ioctl_ops `-> ``vidioc_subscribe_event``, +but the driver must check first if the driver is able to produce events +with specified event id, and then should call +:c:func:`v4l2_event_subscribe` to subscribe the event. + +The elems argument is the size of the event queue for this event. If it is 0, +then the framework will fill in a default value (this depends on the event +type). + +The ops argument allows the driver to specify a number of callbacks: + +.. tabularcolumns:: |p{1.5cm}|p{16.0cm}| + +======== ============================================================== +Callback Description +======== ============================================================== +add called when a new listener gets added (subscribing to the same + event twice will only cause this callback to get called once) +del called when a listener stops listening +replace replace event 'old' with event 'new'. +merge merge event 'old' into event 'new'. +======== ============================================================== + +All 4 callbacks are optional, if you don't want to specify any callbacks +the ops argument itself maybe ``NULL``. + +Unsubscribing an event +~~~~~~~~~~~~~~~~~~~~~~ + +Unsubscribing to an event is via: + + :c:func:`v4l2_event_unsubscribe ` + (:c:type:`fh `, :c:type:`sub `) + +This function is used to implement :c:type:`video_device`-> +:c:type:`ioctl_ops `-> ``vidioc_unsubscribe_event``. +A driver may call :c:func:`v4l2_event_unsubscribe` directly unless it +wants to be involved in unsubscription process. + +The special type ``V4L2_EVENT_ALL`` may be used to unsubscribe all events. The +drivers may want to handle this in a special way. + +Check if there's a pending event +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Checking if there's a pending event is via: + + :c:func:`v4l2_event_pending ` + (:c:type:`fh `) + + +This function returns the number of pending events. Useful when implementing +poll. + +How events work +~~~~~~~~~~~~~~~ + +Events are delivered to user space through the poll system call. The driver +can use :c:type:`v4l2_fh`->wait (a wait_queue_head_t) as the argument for +``poll_wait()``. + +There are standard and private events. New standard events must use the +smallest available event type. The drivers must allocate their events from +their own class starting from class base. Class base is +``V4L2_EVENT_PRIVATE_START`` + n * 1000 where n is the lowest available number. +The first event type in the class is reserved for future use, so the first +available event type is 'class base + 1'. + +An example on how the V4L2 events may be used can be found in the OMAP +3 ISP driver (``drivers/media/platform/ti/omap3isp``). + +A subdev can directly send an event to the :c:type:`v4l2_device` notify +function with ``V4L2_DEVICE_NOTIFY_EVENT``. This allows the bridge to map +the subdev that sends the event to the video node(s) associated with the +subdev that need to be informed about such an event. + +V4L2 event functions and data structures +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +.. kernel-doc:: include/media/v4l2-event.h + -- cgit v1.2.3