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().
  ...

1 files changed, 775 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/v4l/colorspaces-details.rst b/Documentation/userspace-api/media/v4l/colorspaces-details.rst
new file mode 100644
index 000000000..26a4ace42
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/colorspaces-details.rst
@@ -0,0 +1,775 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+********************************
+Detailed Colorspace Descriptions
+********************************
+
+
+.. _col-smpte-170m:
+
+Colorspace SMPTE 170M (V4L2_COLORSPACE_SMPTE170M)
+=================================================
+
+The :ref:`smpte170m` standard defines the colorspace used by NTSC and
+PAL and by SDTV in general. The default transfer function is
+``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
+range. The chromaticities of the primary colors and the white reference
+are:
+
+.. flat-table:: SMPTE 170M Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.630
+      - 0.340
+    * - Green
+      - 0.310
+      - 0.595
+    * - Blue
+      - 0.155
+      - 0.070
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+The red, green and blue chromaticities are also often referred to as the
+SMPTE C set, so this colorspace is sometimes called SMPTE C as well.
+
+The transfer function defined for SMPTE 170M is the same as the one
+defined in Rec. 709.
+
+.. math::
+
+    L' = -1.099(-L)^{0.45} + 0.099 \text{, for } L \le-0.018
+
+    L' = 4.5L \text{, for } -0.018 < L < 0.018
+
+    L' = 1.099L^{0.45} - 0.099 \text{, for } L \ge 0.018
+
+Inverse Transfer function:
+
+.. math::
+
+    L = -\left( \frac{L' - 0.099}{-1.099} \right) ^{\frac{1}{0.45}} \text{, for } L' \le -0.081
+
+    L = \frac{L'}{4.5} \text{, for } -0.081 < L' < 0.081
+
+    L = \left(\frac{L' + 0.099}{1.099}\right)^{\frac{1}{0.45} } \text{, for } L' \ge 0.081
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_601`` encoding:
+
+.. math::
+
+    Y' = 0.2990R' + 0.5870G' + 0.1140B'
+
+    Cb = -0.1687R' - 0.3313G' + 0.5B'
+
+    Cr = 0.5R' - 0.4187G' - 0.0813B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. This conversion to Y'CbCr is identical to the one defined in
+the :ref:`itu601` standard and this colorspace is sometimes called
+BT.601 as well, even though BT.601 does not mention any color primaries.
+
+The default quantization is limited range, but full range is possible
+although rarely seen.
+
+
+.. _col-rec709:
+
+Colorspace Rec. 709 (V4L2_COLORSPACE_REC709)
+============================================
+
+The :ref:`itu709` standard defines the colorspace used by HDTV in
+general. The default transfer function is ``V4L2_XFER_FUNC_709``. The
+default Y'CbCr encoding is ``V4L2_YCBCR_ENC_709``. The default Y'CbCr
+quantization is limited range. The chromaticities of the primary colors
+and the white reference are:
+
+.. flat-table:: Rec. 709 Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.640
+      - 0.330
+    * - Green
+      - 0.300
+      - 0.600
+    * - Blue
+      - 0.150
+      - 0.060
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+The full name of this standard is Rec. ITU-R BT.709-5.
+
+Transfer function. Normally L is in the range [0…1], but for the
+extended gamut xvYCC encoding values outside that range are allowed.
+
+.. math::
+
+    L' = -1.099(-L)^{0.45} + 0.099 \text{, for } L \le -0.018
+
+    L' = 4.5L \text{, for } -0.018 < L < 0.018
+
+    L' = 1.099L^{0.45} - 0.099 \text{, for } L \ge 0.018
+
+Inverse Transfer function:
+
+.. math::
+
+    L = -\left( \frac{L' - 0.099}{-1.099} \right)^\frac{1}{0.45} \text{, for } L' \le -0.081
+
+    L = \frac{L'}{4.5}\text{, for } -0.081 < L' < 0.081
+
+    L = \left(\frac{L' + 0.099}{1.099}\right)^{\frac{1}{0.45} } \text{, for } L' \ge 0.081
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_709`` encoding:
+
+.. math::
+
+    Y' = 0.2126R' + 0.7152G' + 0.0722B'
+
+    Cb = -0.1146R' - 0.3854G' + 0.5B'
+
+    Cr = 0.5R' - 0.4542G' - 0.0458B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5].
+
+The default quantization is limited range, but full range is possible
+although rarely seen.
+
+The ``V4L2_YCBCR_ENC_709`` encoding described above is the default for
+this colorspace, but it can be overridden with ``V4L2_YCBCR_ENC_601``,
+in which case the BT.601 Y'CbCr encoding is used.
+
+Two additional extended gamut Y'CbCr encodings are also possible with
+this colorspace:
+
+The xvYCC 709 encoding (``V4L2_YCBCR_ENC_XV709``, :ref:`xvycc`) is
+similar to the Rec. 709 encoding, but it allows for R', G' and B' values
+that are outside the range [0…1]. The resulting Y', Cb and Cr values are
+scaled and offset according to the limited range formula:
+
+.. math::
+
+    Y' = \frac{219}{256} * (0.2126R' + 0.7152G' + 0.0722B') + \frac{16}{256}
+
+    Cb = \frac{224}{256} * (-0.1146R' - 0.3854G' + 0.5B')
+
+    Cr = \frac{224}{256} * (0.5R' - 0.4542G' - 0.0458B')
+
+The xvYCC 601 encoding (``V4L2_YCBCR_ENC_XV601``, :ref:`xvycc`) is
+similar to the BT.601 encoding, but it allows for R', G' and B' values
+that are outside the range [0…1]. The resulting Y', Cb and Cr values are
+scaled and offset according to the limited range formula:
+
+.. math::
+
+    Y' = \frac{219}{256} * (0.2990R' + 0.5870G' + 0.1140B') + \frac{16}{256}
+
+    Cb = \frac{224}{256} * (-0.1687R' - 0.3313G' + 0.5B')
+
+    Cr = \frac{224}{256} * (0.5R' - 0.4187G' - 0.0813B')
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5] and quantized without further scaling or offsets.
+The non-standard xvYCC 709 or xvYCC 601 encodings can be
+used by selecting ``V4L2_YCBCR_ENC_XV709`` or ``V4L2_YCBCR_ENC_XV601``.
+As seen by the xvYCC formulas these encodings always use limited range quantization,
+there is no full range variant. The whole point of these extended gamut encodings
+is that values outside the limited range are still valid, although they
+map to R', G' and B' values outside the [0…1] range and are therefore outside
+the Rec. 709 colorspace gamut.
+
+
+.. _col-srgb:
+
+Colorspace sRGB (V4L2_COLORSPACE_SRGB)
+======================================
+
+The :ref:`srgb` standard defines the colorspace used by most webcams
+and computer graphics. The default transfer function is
+``V4L2_XFER_FUNC_SRGB``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited range.
+
+Note that the :ref:`sycc` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+
+The chromaticities of the primary colors and the white reference are:
+
+.. flat-table:: sRGB Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.640
+      - 0.330
+    * - Green
+      - 0.300
+      - 0.600
+    * - Blue
+      - 0.150
+      - 0.060
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+These chromaticities are identical to the Rec. 709 colorspace.
+
+Transfer function. Note that negative values for L are only used by the
+Y'CbCr conversion.
+
+.. math::
+
+    L' = -1.055(-L)^{\frac{1}{2.4} } + 0.055\text{, for }L < -0.0031308
+
+    L' = 12.92L\text{, for }-0.0031308 \le L \le 0.0031308
+
+    L' = 1.055L ^{\frac{1}{2.4} } - 0.055\text{, for }0.0031308 < L \le 1
+
+Inverse Transfer function:
+
+.. math::
+
+    L = -((-L' + 0.055) / 1.055) ^{2.4}\text{, for }L' < -0.04045
+
+    L = L' / 12.92\text{, for }-0.04045 \le L' \le 0.04045
+
+    L = ((L' + 0.055) / 1.055) ^{2.4}\text{, for }L' > 0.04045
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_601`` encoding as defined by :ref:`sycc`:
+
+.. math::
+
+    Y' = 0.2990R' + 0.5870G' + 0.1140B'
+
+    Cb = -0.1687R' - 0.3313G' + 0.5B'
+
+    Cr = 0.5R' - 0.4187G' - 0.0813B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. This transform is identical to one defined in SMPTE
+170M/BT.601. The Y'CbCr quantization is limited range.
+
+
+.. _col-oprgb:
+
+Colorspace opRGB (V4L2_COLORSPACE_OPRGB)
+===============================================
+
+The :ref:`oprgb` standard defines the colorspace used by computer
+graphics that use the opRGB colorspace. The default transfer function is
+``V4L2_XFER_FUNC_OPRGB``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
+range.
+
+Note that the :ref:`oprgb` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+
+The chromaticities of the primary colors and the white reference are:
+
+.. flat-table:: opRGB Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.6400
+      - 0.3300
+    * - Green
+      - 0.2100
+      - 0.7100
+    * - Blue
+      - 0.1500
+      - 0.0600
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+
+Transfer function:
+
+.. math::
+
+    L' = L ^{\frac{1}{2.19921875}}
+
+Inverse Transfer function:
+
+.. math::
+
+    L = L'^{(2.19921875)}
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_601`` encoding:
+
+.. math::
+
+    Y' = 0.2990R' + 0.5870G' + 0.1140B'
+
+    Cb = -0.1687R' - 0.3313G' + 0.5B'
+
+    Cr = 0.5R' - 0.4187G' - 0.0813B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. This transform is identical to one defined in SMPTE
+170M/BT.601. The Y'CbCr quantization is limited range.
+
+
+.. _col-bt2020:
+
+Colorspace BT.2020 (V4L2_COLORSPACE_BT2020)
+===========================================
+
+The :ref:`itu2020` standard defines the colorspace used by Ultra-high
+definition television (UHDTV). The default transfer function is
+``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_BT2020``. The default Y'CbCr quantization is limited range.
+The chromaticities of the primary colors and the white reference are:
+
+.. flat-table:: BT.2020 Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.708
+      - 0.292
+    * - Green
+      - 0.170
+      - 0.797
+    * - Blue
+      - 0.131
+      - 0.046
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+
+Transfer function (same as Rec. 709):
+
+.. math::
+
+    L' = 4.5L\text{, for }0 \le L < 0.018
+
+    L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
+
+Inverse Transfer function:
+
+.. math::
+
+    L = L' / 4.5\text{, for } L' < 0.081
+
+    L = \left( \frac{L' + 0.099}{1.099}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
+
+Please note that while Rec. 709 is defined as the default transfer function
+by the :ref:`itu2020` standard, in practice this colorspace is often used
+with the :ref:`xf-smpte-2084`. In particular Ultra HD Blu-ray discs use
+this combination.
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_BT2020`` encoding:
+
+.. math::
+
+    Y' = 0.2627R' + 0.6780G' + 0.0593B'
+
+    Cb = -0.1396R' - 0.3604G' + 0.5B'
+
+    Cr = 0.5R' - 0.4598G' - 0.0402B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. The Y'CbCr quantization is limited range.
+
+There is also an alternate constant luminance R'G'B' to Yc'CbcCrc
+(``V4L2_YCBCR_ENC_BT2020_CONST_LUM``) encoding:
+
+Luma:
+
+.. math::
+    :nowrap:
+
+    \begin{align*}
+    Yc' = (0.2627R + 0.6780G + 0.0593B)'& \\
+    B' - Yc' \le 0:& \\
+        &Cbc = (B' - Yc') / 1.9404 \\
+    B' - Yc' > 0: & \\
+        &Cbc = (B' - Yc') / 1.5816 \\
+    R' - Yc' \le 0:& \\
+        &Crc = (R' - Y') / 1.7184 \\
+    R' - Yc' > 0:& \\
+        &Crc = (R' - Y') / 0.9936
+    \end{align*}
+
+Yc' is clamped to the range [0…1] and Cbc and Crc are clamped to the
+range [-0.5…0.5]. The Yc'CbcCrc quantization is limited range.
+
+
+.. _col-dcip3:
+
+Colorspace DCI-P3 (V4L2_COLORSPACE_DCI_P3)
+==========================================
+
+The :ref:`smpte431` standard defines the colorspace used by cinema
+projectors that use the DCI-P3 colorspace. The default transfer function
+is ``V4L2_XFER_FUNC_DCI_P3``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_709``. The default Y'CbCr quantization is limited range.
+
+.. note::
+
+   Note that this colorspace standard does not specify a
+   Y'CbCr encoding since it is not meant to be encoded to Y'CbCr. So this
+   default Y'CbCr encoding was picked because it is the HDTV encoding.
+
+The chromaticities of the primary colors and the white reference are:
+
+
+.. flat-table:: DCI-P3 Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.6800
+      - 0.3200
+    * - Green
+      - 0.2650
+      - 0.6900
+    * - Blue
+      - 0.1500
+      - 0.0600
+    * - White Reference
+      - 0.3140
+      - 0.3510
+
+
+
+Transfer function:
+
+.. math::
+
+    L' = L^{\frac{1}{2.6}}
+
+Inverse Transfer function:
+
+.. math::
+
+    L = L'^{(2.6)}
+
+Y'CbCr encoding is not specified. V4L2 defaults to Rec. 709.
+
+
+.. _col-smpte-240m:
+
+Colorspace SMPTE 240M (V4L2_COLORSPACE_SMPTE240M)
+=================================================
+
+The :ref:`smpte240m` standard was an interim standard used during the
+early days of HDTV (1988-1998). It has been superseded by Rec. 709. The
+default transfer function is ``V4L2_XFER_FUNC_SMPTE240M``. The default
+Y'CbCr encoding is ``V4L2_YCBCR_ENC_SMPTE240M``. The default Y'CbCr
+quantization is limited range. The chromaticities of the primary colors
+and the white reference are:
+
+
+.. flat-table:: SMPTE 240M Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.630
+      - 0.340
+    * - Green
+      - 0.310
+      - 0.595
+    * - Blue
+      - 0.155
+      - 0.070
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+These chromaticities are identical to the SMPTE 170M colorspace.
+
+Transfer function:
+
+.. math::
+
+    L' = 4L\text{, for } 0 \le L < 0.0228
+
+    L' = 1.1115L ^{0.45} - 0.1115\text{, for } 0.0228 \le L \le 1
+
+Inverse Transfer function:
+
+.. math::
+
+    L = \frac{L'}{4}\text{, for } 0 \le L' < 0.0913
+
+    L = \left( \frac{L' + 0.1115}{1.1115}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.0913
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_SMPTE240M`` encoding:
+
+.. math::
+
+    Y' = 0.2122R' + 0.7013G' + 0.0865B'
+
+    Cb = -0.1161R' - 0.3839G' + 0.5B'
+
+    Cr = 0.5R' - 0.4451G' - 0.0549B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the
+range [-0.5…0.5]. The Y'CbCr quantization is limited range.
+
+
+.. _col-sysm:
+
+Colorspace NTSC 1953 (V4L2_COLORSPACE_470_SYSTEM_M)
+===================================================
+
+This standard defines the colorspace used by NTSC in 1953. In practice
+this colorspace is obsolete and SMPTE 170M should be used instead. The
+default transfer function is ``V4L2_XFER_FUNC_709``. The default Y'CbCr
+encoding is ``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is
+limited range. The chromaticities of the primary colors and the white
+reference are:
+
+
+.. flat-table:: NTSC 1953 Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.67
+      - 0.33
+    * - Green
+      - 0.21
+      - 0.71
+    * - Blue
+      - 0.14
+      - 0.08
+    * - White Reference (C)
+      - 0.310
+      - 0.316
+
+
+.. note::
+
+   This colorspace uses Illuminant C instead of D65 as the white
+   reference. To correctly convert an image in this colorspace to another
+   that uses D65 you need to apply a chromatic adaptation algorithm such as
+   the Bradford method.
+
+The transfer function was never properly defined for NTSC 1953. The Rec.
+709 transfer function is recommended in the literature:
+
+.. math::
+
+    L' = 4.5L\text{, for } 0 \le L < 0.018
+
+    L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
+
+Inverse Transfer function:
+
+.. math::
+
+    L = \frac{L'}{4.5} \text{, for } L' < 0.081
+
+    L = \left( \frac{L' + 0.099}{1.099}\right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_601`` encoding:
+
+.. math::
+
+    Y' = 0.2990R' + 0.5870G' + 0.1140B'
+
+    Cb = -0.1687R' - 0.3313G' + 0.5B'
+
+    Cr = 0.5R' - 0.4187G' - 0.0813B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is
+identical to one defined in SMPTE 170M/BT.601.
+
+
+.. _col-sysbg:
+
+Colorspace EBU Tech. 3213 (V4L2_COLORSPACE_470_SYSTEM_BG)
+=========================================================
+
+The :ref:`tech3213` standard defines the colorspace used by PAL/SECAM
+in 1975. Note that this colorspace is not supported by the HDMI interface.
+Instead :ref:`tech3321` recommends that Rec. 709 is used instead for HDMI.
+The default transfer function is
+``V4L2_XFER_FUNC_709``. The default Y'CbCr encoding is
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
+range. The chromaticities of the primary colors and the white reference
+are:
+
+
+.. flat-table:: EBU Tech. 3213 Chromaticities
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - Color
+      - x
+      - y
+    * - Red
+      - 0.64
+      - 0.33
+    * - Green
+      - 0.29
+      - 0.60
+    * - Blue
+      - 0.15
+      - 0.06
+    * - White Reference (D65)
+      - 0.3127
+      - 0.3290
+
+
+
+The transfer function was never properly defined for this colorspace.
+The Rec. 709 transfer function is recommended in the literature:
+
+.. math::
+
+    L' = 4.5L\text{, for } 0 \le L < 0.018
+
+    L' = 1.099L ^{0.45} - 0.099\text{, for } 0.018 \le L \le 1
+
+Inverse Transfer function:
+
+.. math::
+
+    L = \frac{L'}{4.5} \text{, for } L' < 0.081
+
+    L = \left(\frac{L' + 0.099}{1.099} \right) ^{\frac{1}{0.45} }\text{, for } L' \ge 0.081
+
+The luminance (Y') and color difference (Cb and Cr) are obtained with
+the following ``V4L2_YCBCR_ENC_601`` encoding:
+
+.. math::
+
+    Y' = 0.2990R' + 0.5870G' + 0.1140B'
+
+    Cb = -0.1687R' - 0.3313G' + 0.5B'
+
+    Cr = 0.5R' - 0.4187G' - 0.0813B'
+
+Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
+[-0.5…0.5]. The Y'CbCr quantization is limited range. This transform is
+identical to one defined in SMPTE 170M/BT.601.
+
+
+.. _col-jpeg:
+
+Colorspace JPEG (V4L2_COLORSPACE_JPEG)
+======================================
+
+This colorspace defines the colorspace used by most (Motion-)JPEG
+formats. The chromaticities of the primary colors and the white
+reference are identical to sRGB. The transfer function use is
+``V4L2_XFER_FUNC_SRGB``. The Y'CbCr encoding is ``V4L2_YCBCR_ENC_601``
+with full range quantization where Y' is scaled to [0…255] and Cb/Cr are
+scaled to [-128…128] and then clipped to [-128…127].
+
+.. note::
+
+   The JPEG standard does not actually store colorspace
+   information. So if something other than sRGB is used, then the driver
+   will have to set that information explicitly. Effectively
+   ``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for
+   ``V4L2_COLORSPACE_SRGB``, ``V4L2_XFER_FUNC_SRGB``, ``V4L2_YCBCR_ENC_601``
+   and ``V4L2_QUANTIZATION_FULL_RANGE``.
+
+***************************************
+Detailed Transfer Function Descriptions
+***************************************
+
+.. _xf-smpte-2084:
+
+Transfer Function SMPTE 2084 (V4L2_XFER_FUNC_SMPTE2084)
+=======================================================
+
+The :ref:`smpte2084` standard defines the transfer function used by
+High Dynamic Range content.
+
+Constants:
+    m1 = (2610 / 4096) / 4
+
+    m2 = (2523 / 4096) * 128
+
+    c1 = 3424 / 4096
+
+    c2 = (2413 / 4096) * 32
+
+    c3 = (2392 / 4096) * 32
+
+Transfer function:
+    L' = ((c1 + c2 * L\ :sup:`m1`) / (1 + c3 * L\ :sup:`m1`))\ :sup:`m2`
+
+Inverse Transfer function:
+    L = (max(L':sup:`1/m2` - c1, 0) / (c2 - c3 *
+    L'\ :sup:`1/m2`))\ :sup:`1/m1`
+
+Take care when converting between this transfer function and non-HDR transfer
+functions: the linear RGB values [0…1] of HDR content map to a luminance range
+of 0 to 10000 cd/m\ :sup:`2` whereas the linear RGB values of non-HDR (aka
+Standard Dynamic Range or SDR) map to a luminance range of 0 to 100 cd/m\ :sup:`2`.
+
+To go from SDR to HDR you will have to divide L by 100 first. To go in the other
+direction you will have to multiply L by 100. Of course, this clamps all
+luminance values over 100 cd/m\ :sup:`2` to 100 cd/m\ :sup:`2`.
+
+There are better methods, see e.g. :ref:`colimg` for more in-depth information
+about this.