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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/userspace-api/media/v4l/field-order.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
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().
...
Diffstat (limited to 'Documentation/userspace-api/media/v4l/field-order.rst')
-rw-r--r-- | Documentation/userspace-api/media/v4l/field-order.rst | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/field-order.rst b/Documentation/userspace-api/media/v4l/field-order.rst new file mode 100644 index 000000000..9a0ed8fc5 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/field-order.rst @@ -0,0 +1,165 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _field-order: + +*********** +Field Order +*********** + +We have to distinguish between progressive and interlaced video. +Progressive video transmits all lines of a video image sequentially. +Interlaced video divides an image into two fields, containing only the +odd and even lines of the image, respectively. Alternating the so called +odd and even field are transmitted, and due to a small delay between +fields a cathode ray TV displays the lines interleaved, yielding the +original frame. This curious technique was invented because at refresh +rates similar to film the image would fade out too quickly. Transmitting +fields reduces the flicker without the necessity of doubling the frame +rate and with it the bandwidth required for each channel. + +It is important to understand a video camera does not expose one frame +at a time, merely transmitting the frames separated into fields. The +fields are in fact captured at two different instances in time. An +object on screen may well move between one field and the next. For +applications analysing motion it is of paramount importance to recognize +which field of a frame is older, the *temporal order*. + +When the driver provides or accepts images field by field rather than +interleaved, it is also important applications understand how the fields +combine to frames. We distinguish between top (aka odd) and bottom (aka +even) fields, the *spatial order*: The first line of the top field is +the first line of an interlaced frame, the first line of the bottom +field is the second line of that frame. + +However because fields were captured one after the other, arguing +whether a frame commences with the top or bottom field is pointless. Any +two successive top and bottom, or bottom and top fields yield a valid +frame. Only when the source was progressive to begin with, e. g. when +transferring film to video, two fields may come from the same frame, +creating a natural order. + +Counter to intuition the top field is not necessarily the older field. +Whether the older field contains the top or bottom lines is a convention +determined by the video standard. Hence the distinction between temporal +and spatial order of fields. The diagrams below should make this +clearer. + +In V4L it is assumed that all video cameras transmit fields on the media +bus in the same order they were captured, so if the top field was +captured first (is the older field), the top field is also transmitted +first on the bus. + +All video capture and output devices must report the current field +order. Some drivers may permit the selection of a different order, to +this end applications initialize the ``field`` field of struct +:c:type:`v4l2_pix_format` before calling the +:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. If this is not desired it +should have the value ``V4L2_FIELD_ANY`` (0). + + +enum v4l2_field +=============== + +.. c:type:: v4l2_field + +.. tabularcolumns:: |p{5.8cm}|p{0.6cm}|p{10.9cm}| + +.. cssclass:: longtable + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + * - ``V4L2_FIELD_ANY`` + - 0 + - Applications request this field order when any field format + is acceptable. Drivers choose depending on hardware capabilities or + e.g. the requested image size, and return the actual field order. + Drivers must never return ``V4L2_FIELD_ANY``. + If multiple field orders are possible the + driver must choose one of the possible field orders during + :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or + :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`. struct + :c:type:`v4l2_buffer` ``field`` can never be + ``V4L2_FIELD_ANY``. + * - ``V4L2_FIELD_NONE`` + - 1 + - Images are in progressive (frame-based) format, not interlaced + (field-based). + * - ``V4L2_FIELD_TOP`` + - 2 + - Images consist of the top (aka odd) field only. + * - ``V4L2_FIELD_BOTTOM`` + - 3 + - Images consist of the bottom (aka even) field only. Applications + may wish to prevent a device from capturing interlaced images + because they will have "comb" or "feathering" artefacts around + moving objects. + * - ``V4L2_FIELD_INTERLACED`` + - 4 + - Images contain both fields, interleaved line by line. The temporal + order of the fields (whether the top or bottom field is older) + depends on the current video standard. In M/NTSC the bottom + field is the older field. In all other standards the top field + is the older field. + * - ``V4L2_FIELD_SEQ_TB`` + - 5 + - Images contain both fields, the top field lines are stored first + in memory, immediately followed by the bottom field lines. Fields + are always stored in temporal order, the older one first in + memory. Image sizes refer to the frame, not fields. + * - ``V4L2_FIELD_SEQ_BT`` + - 6 + - Images contain both fields, the bottom field lines are stored + first in memory, immediately followed by the top field lines. + Fields are always stored in temporal order, the older one first in + memory. Image sizes refer to the frame, not fields. + * - ``V4L2_FIELD_ALTERNATE`` + - 7 + - The two fields of a frame are passed in separate buffers, in + temporal order, i. e. the older one first. To indicate the field + parity (whether the current field is a top or bottom field) the + driver or application, depending on data direction, must set + struct :c:type:`v4l2_buffer` ``field`` to + ``V4L2_FIELD_TOP`` or ``V4L2_FIELD_BOTTOM``. Any two successive + fields pair to build a frame. If fields are successive, without + any dropped fields between them (fields can drop individually), + can be determined from the struct + :c:type:`v4l2_buffer` ``sequence`` field. This + format cannot be selected when using the read/write I/O method + since there is no way to communicate if a field was a top or + bottom field. + * - ``V4L2_FIELD_INTERLACED_TB`` + - 8 + - Images contain both fields, interleaved line by line, top field + first. The top field is the older field. + * - ``V4L2_FIELD_INTERLACED_BT`` + - 9 + - Images contain both fields, interleaved line by line, top field + first. The bottom field is the older field. + + + +.. _fieldseq-tb: + +Field Order, Top Field First Transmitted +======================================== + +.. kernel-figure:: fieldseq_tb.svg + :alt: fieldseq_tb.svg + :align: center + + Field Order, Top Field First Transmitted + + +.. _fieldseq-bt: + +Field Order, Bottom Field First Transmitted +=========================================== + +.. kernel-figure:: fieldseq_bt.svg + :alt: fieldseq_bt.svg + :align: center + + Field Order, Bottom Field First Transmitted |