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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/driver-api/media/camera-sensor.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/driver-api/media/camera-sensor.rst')
-rw-r--r-- | Documentation/driver-api/media/camera-sensor.rst | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst new file mode 100644 index 000000000..c7d4891bd --- /dev/null +++ b/Documentation/driver-api/media/camera-sensor.rst @@ -0,0 +1,153 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Writing camera sensor drivers +============================= + +CSI-2 and parallel (BT.601 and BT.656) busses +--------------------------------------------- + +Please see :ref:`transmitter-receiver`. + +Handling clocks +--------------- + +Camera sensors have an internal clock tree including a PLL and a number of +divisors. The clock tree is generally configured by the driver based on a few +input parameters that are specific to the hardware:: the external clock frequency +and the link frequency. The two parameters generally are obtained from system +firmware. **No other frequencies should be used in any circumstances.** + +The reason why the clock frequencies are so important is that the clock signals +come out of the SoC, and in many cases a specific frequency is designed to be +used in the system. Using another frequency may cause harmful effects +elsewhere. Therefore only the pre-determined frequencies are configurable by the +user. + +ACPI +~~~~ + +Read the ``clock-frequency`` _DSD property to denote the frequency. The driver +can rely on this frequency being used. + +Devicetree +~~~~~~~~~~ + +The currently preferred way to achieve this is using ``assigned-clocks``, +``assigned-clock-parents`` and ``assigned-clock-rates`` properties. See +``Documentation/devicetree/bindings/clock/clock-bindings.txt`` for more +information. The driver then gets the frequency using ``clk_get_rate()``. + +This approach has the drawback that there's no guarantee that the frequency +hasn't been modified directly or indirectly by another driver, or supported by +the board's clock tree to begin with. Changes to the Common Clock Framework API +are required to ensure reliability. + +Frame size +---------- + +There are two distinct ways to configure the frame size produced by camera +sensors. + +Freely configurable camera sensor drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Freely configurable camera sensor drivers expose the device's internal +processing pipeline as one or more sub-devices with different cropping and +scaling configurations. The output size of the device is the result of a series +of cropping and scaling operations from the device's pixel array's size. + +An example of such a driver is the CCS driver (see ``drivers/media/i2c/ccs``). + +Register list based drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Register list based drivers generally, instead of able to configure the device +they control based on user requests, are limited to a number of preset +configurations that combine a number of different parameters that on hardware +level are independent. How a driver picks such configuration is based on the +format set on a source pad at the end of the device's internal pipeline. + +Most sensor drivers are implemented this way, see e.g. +``drivers/media/i2c/imx319.c`` for an example. + +Frame interval configuration +---------------------------- + +There are two different methods for obtaining possibilities for different frame +intervals as well as configuring the frame interval. Which one to implement +depends on the type of the device. + +Raw camera sensors +~~~~~~~~~~~~~~~~~~ + +Instead of a high level parameter such as frame interval, the frame interval is +a result of the configuration of a number of camera sensor implementation +specific parameters. Luckily, these parameters tend to be the same for more or +less all modern raw camera sensors. + +The frame interval is calculated using the following equation:: + + frame interval = (analogue crop width + horizontal blanking) * + (analogue crop height + vertical blanking) / pixel rate + +The formula is bus independent and is applicable for raw timing parameters on +large variety of devices beyond camera sensors. Devices that have no analogue +crop, use the full source image size, i.e. pixel array size. + +Horizontal and vertical blanking are specified by ``V4L2_CID_HBLANK`` and +``V4L2_CID_VBLANK``, respectively. The unit of the ``V4L2_CID_HBLANK`` control +is pixels and the unit of the ``V4L2_CID_VBLANK`` is lines. The pixel rate in +the sensor's **pixel array** is specified by ``V4L2_CID_PIXEL_RATE`` in the same +sub-device. The unit of that control is pixels per second. + +Register list based drivers need to implement read-only sub-device nodes for the +purpose. Devices that are not register list based need these to configure the +device's internal processing pipeline. + +The first entity in the linear pipeline is the pixel array. The pixel array may +be followed by other entities that are there to allow configuring binning, +skipping, scaling or digital crop :ref:`v4l2-subdev-selections`. + +USB cameras etc. devices +~~~~~~~~~~~~~~~~~~~~~~~~ + +USB video class hardware, as well as many cameras offering a similar higher +level interface natively, generally use the concept of frame interval (or frame +rate) on device level in firmware or hardware. This means lower level controls +implemented by raw cameras may not be used on uAPI (or even kAPI) to control the +frame interval on these devices. + +Power management +---------------- + +Always use runtime PM to manage the power states of your device. Camera sensor +drivers are in no way special in this respect: they are responsible for +controlling the power state of the device they otherwise control as well. In +general, the device must be powered on at least when its registers are being +accessed and when it is streaming. + +Existing camera sensor drivers may rely on the old +struct v4l2_subdev_core_ops->s_power() callback for bridge or ISP drivers to +manage their power state. This is however **deprecated**. If you feel you need +to begin calling an s_power from an ISP or a bridge driver, instead please add +runtime PM support to the sensor driver you are using. Likewise, new drivers +should not use s_power. + +Please see examples in e.g. ``drivers/media/i2c/ov8856.c`` and +``drivers/media/i2c/ccs/ccs-core.c``. The two drivers work in both ACPI +and DT based systems. + +Control framework +~~~~~~~~~~~~~~~~~ + +``v4l2_ctrl_handler_setup()`` function may not be used in the device's runtime +PM ``runtime_resume`` callback, as it has no way to figure out the power state +of the device. This is because the power state of the device is only changed +after the power state transition has taken place. The ``s_ctrl`` callback can be +used to obtain device's power state after the power state transition: + +.. c:function:: int pm_runtime_get_if_in_use(struct device *dev); + +The function returns a non-zero value if it succeeded getting the power count or +runtime PM was disabled, in either of which cases the driver may proceed to +access the device. |