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, 513 insertions, 0 deletions

diff --git a/Documentation/driver-api/media/drivers/vidtv.rst b/Documentation/driver-api/media/drivers/vidtv.rst
new file mode 100644
index 000000000..673bdff91
--- /dev/null
+++ b/Documentation/driver-api/media/drivers/vidtv.rst
@@ -0,0 +1,513 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================================
+vidtv: Virtual Digital TV driver
+================================
+
+Author: Daniel W. S. Almeida <dwlsalmeida@gmail.com>, June 2020.
+
+Background
+----------
+
+Vidtv is a virtual DVB driver that aims to serve as a reference for driver
+writers by serving as a template. It also validates the existing media DVB
+APIs, thus helping userspace application writers.
+
+Currently, it consists of:
+
+- A fake tuner driver, which will report a bad signal quality if the chosen
+  frequency is too far away from a table of valid frequencies for a
+  particular delivery system.
+
+- A fake demod driver, which will constantly poll the fake signal quality
+  returned by the tuner, simulating a device that can lose/reacquire a lock
+  on the signal depending on the CNR levels.
+
+- A fake bridge driver, which is the module responsible for modprobing the
+  fake tuner and demod modules and implementing the demux logic. This module
+  takes parameters at initialization that will dictate how the simulation
+  behaves.
+
+- Code reponsible for encoding a valid MPEG Transport Stream, which is then
+  passed to the bridge driver. This fake stream contains some hardcoded content.
+  For now, we have a single, audio-only channel containing a single MPEG
+  Elementary Stream, which in turn contains a SMPTE 302m encoded sine-wave.
+  Note that this particular encoder was chosen because it is the easiest
+  way to encode PCM audio data in a MPEG Transport Stream.
+
+Building vidtv
+--------------
+vidtv is a test driver and thus is **not** enabled by default when
+compiling the kernel.
+
+In order to enable compilation of vidtv:
+
+- Enable **DVB_TEST_DRIVERS**, then
+- Enable **DVB_VIDTV**
+
+When compiled as a module, expect the following .ko files:
+
+- dvb_vidtv_tuner.ko
+
+- dvb_vidtv_demod.ko
+
+- dvb_vidtv_bridge.ko
+
+Running vidtv
+-------------
+When compiled as a module, run::
+
+	modprobe vidtv
+
+That's it! The bridge driver will initialize the tuner and demod drivers as
+part of its own initialization.
+
+By default, it will accept the following frequencies:
+
+	- 474 MHz for DVB-T/T2/C;
+	- 11,362 GHz for DVB-S/S2.
+
+For satellite systems, the driver simulates an universal extended
+LNBf, with frequencies at Ku-Band, ranging from 10.7 GHz to 12.75 GHz.
+
+You can optionally define some command-line arguments to vidtv.
+
+Command-line arguments to vidtv
+-------------------------------
+Below is a list of all arguments that can be supplied to vidtv:
+
+drop_tslock_prob_on_low_snr
+	Probability of losing the TS lock if the signal quality is bad.
+	This probability be used by the fake demodulator driver to
+	eventually return a status of 0 when the signal quality is not
+	good.
+
+recover_tslock_prob_on_good_snr:
+	Probability recovering the TS lock when the signal improves. This
+	probability be used by the fake demodulator driver to eventually
+	return a status of 0x1f when/if the signal quality improves.
+
+mock_power_up_delay_msec
+	Simulate a power up delay.  Default: 0.
+
+mock_tune_delay_msec
+	Simulate a tune delay.  Default 0.
+
+vidtv_valid_dvb_t_freqs
+	Valid DVB-T frequencies to simulate, in Hz.
+
+vidtv_valid_dvb_c_freqs
+	Valid DVB-C frequencies to simulate, in Hz.
+
+vidtv_valid_dvb_s_freqs
+	Valid DVB-S/S2 frequencies to simulate at Ku-Band, in kHz.
+
+max_frequency_shift_hz,
+	Maximum shift in HZ allowed when tuning in a channel.
+
+si_period_msec
+	How often to send SI packets.  Default: 40ms.
+
+pcr_period_msec
+	How often to send PCR packets.  Default: 40ms.
+
+mux_rate_kbytes_sec
+	Attempt to maintain this bit rate by inserting TS null packets, if
+	necessary.  Default: 4096.
+
+pcr_pid,
+	PCR PID for all channels.  Default: 0x200.
+
+mux_buf_sz_pkts,
+	Size for the mux buffer in multiples of 188 bytes.
+
+vidtv internal structure
+------------------------
+The kernel modules are split in the following way:
+
+vidtv_tuner.[ch]
+	Implements a fake tuner DVB driver.
+
+vidtv_demod.[ch]
+	Implements a fake demodulator DVB driver.
+
+vidtv_bridge.[ch]
+	Implements a bridge driver.
+
+The MPEG related code is split in the following way:
+
+vidtv_ts.[ch]
+	Code to work with MPEG TS packets, such as TS headers, adaptation
+	fields, PCR packets and NULL packets.
+
+vidtv_psi.[ch]
+	This is the PSI generator.  PSI packets contain general information
+	about a MPEG Transport Stream.  A PSI generator is needed so
+	userspace apps can retrieve information about the Transport Stream
+	and eventually tune into a (dummy) channel.
+
+	Because the generator is implemented in a separate file, it can be
+	reused elsewhere in the media subsystem.
+
+	Currently vidtv supports working with 5 PSI tables: PAT, PMT,
+	SDT, NIT and EIT.
+
+	The specification for PAT and PMT can be found in *ISO 13818-1:
+	Systems*, while the specification for the SDT, NIT, EIT can be found in *ETSI
+	EN 300 468: Specification for Service Information (SI) in DVB
+	systems*.
+
+	It isn't strictly necessary, but using a real TS file helps when
+	debugging PSI tables. Vidtv currently tries to replicate the PSI
+	structure found in this file: `TS1Globo.ts
+	<https://tsduck.io/streams/brazil-isdb-tb/TS1globo.ts>`_.
+
+	A good way to visualize the structure of streams is by using
+	`DVBInspector <https://sourceforge.net/projects/dvbinspector/>`_.
+
+vidtv_pes.[ch]
+	Implements the PES logic to convert encoder data into MPEG TS
+	packets. These can then be fed into a TS multiplexer and eventually
+	into userspace.
+
+vidtv_encoder.h
+	An interface for vidtv encoders. New encoders can be added to this
+	driver by implementing the calls in this file.
+
+vidtv_s302m.[ch]
+	Implements a S302M encoder to make it possible to insert PCM audio
+	data in the generated MPEG Transport Stream. The relevant
+	specification is available online as *SMPTE 302M-2007: Television -
+	Mapping of AES3 Data into MPEG-2 Transport Stream*.
+
+
+	The resulting MPEG Elementary Stream is conveyed in a private
+	stream with a S302M registration descriptor attached.
+
+	This shall enable passing an audio signal into userspace so it can
+	be decoded and played by media software. The corresponding decoder
+	in ffmpeg is located in 'libavcodec/s302m.c' and is experimental.
+
+vidtv_channel.[ch]
+	Implements a 'channel' abstraction.
+
+	When vidtv boots, it will create some hardcoded channels:
+
+	#. Their services will be concatenated to populate the SDT.
+
+	#. Their programs will be concatenated to populate the PAT
+
+	#. Their events will be concatenated to populate the EIT
+
+	#. For each program in the PAT, a PMT section will be created
+
+	#. The PMT section for a channel will be assigned its streams.
+
+	#. Every stream will have its corresponding encoder polled in a
+	   loop to produce TS packets.
+	   These packets may be interleaved by the muxer and then delivered
+	   to the bridge.
+
+vidtv_mux.[ch]
+	Implements a MPEG TS mux, loosely based on the ffmpeg
+	implementation in "libavcodec/mpegtsenc.c"
+
+	The muxer runs a loop which is responsible for:
+
+	#. Keeping track of the amount of time elapsed since the last
+	   iteration.
+
+	#. Polling encoders in order to fetch 'elapsed_time' worth of data.
+
+	#. Inserting PSI and/or PCR packets, if needed.
+
+	#. Padding the resulting stream with NULL packets if
+	   necessary in order to maintain the chosen bit rate.
+
+	#. Delivering the resulting TS packets to the bridge
+	   driver so it can pass them to the demux.
+
+Testing vidtv with v4l-utils
+----------------------------
+
+Using the tools in v4l-utils is a great way to test and inspect the output of
+vidtv. It is hosted here: `v4l-utils Documentation
+<https://linuxtv.org/wiki/index.php/V4l-utils>`_.
+
+From its webpage::
+
+	The v4l-utils are a series of packages for handling media devices.
+
+	It is hosted at http://git.linuxtv.org/v4l-utils.git, and packaged
+	on most distributions.
+
+	It provides a series of libraries and utilities to be used to
+	control several aspect of the media boards.
+
+
+Start by installing v4l-utils and then modprobing vidtv::
+
+	modprobe dvb_vidtv_bridge
+
+If the driver is OK, it should load and its probing code will run. This will
+pull in the tuner and demod drivers.
+
+Using dvb-fe-tool
+~~~~~~~~~~~~~~~~~
+
+The first step to check whether the demod loaded successfully is to run::
+
+	$ dvb-fe-tool
+	Device Dummy demod for DVB-T/T2/C/S/S2 (/dev/dvb/adapter0/frontend0) capabilities:
+	    CAN_FEC_1_2
+	    CAN_FEC_2_3
+	    CAN_FEC_3_4
+	    CAN_FEC_4_5
+	    CAN_FEC_5_6
+	    CAN_FEC_6_7
+	    CAN_FEC_7_8
+	    CAN_FEC_8_9
+	    CAN_FEC_AUTO
+	    CAN_GUARD_INTERVAL_AUTO
+	    CAN_HIERARCHY_AUTO
+	    CAN_INVERSION_AUTO
+	    CAN_QAM_16
+	    CAN_QAM_32
+	    CAN_QAM_64
+	    CAN_QAM_128
+	    CAN_QAM_256
+	    CAN_QAM_AUTO
+	    CAN_QPSK
+	    CAN_TRANSMISSION_MODE_AUTO
+	DVB API Version 5.11, Current v5 delivery system: DVBC/ANNEX_A
+	Supported delivery systems:
+	    DVBT
+	    DVBT2
+	    [DVBC/ANNEX_A]
+	    DVBS
+	    DVBS2
+	Frequency range for the current standard:
+	From:            51.0 MHz
+	To:              2.15 GHz
+	Step:            62.5 kHz
+	Tolerance:       29.5 MHz
+	Symbol rate ranges for the current standard:
+	From:            1.00 MBauds
+	To:              45.0 MBauds
+
+This should return what is currently set up at the demod struct, i.e.::
+
+	static const struct dvb_frontend_ops vidtv_demod_ops = {
+		.delsys = {
+			SYS_DVBT,
+			SYS_DVBT2,
+			SYS_DVBC_ANNEX_A,
+			SYS_DVBS,
+			SYS_DVBS2,
+		},
+
+		.info = {
+			.name                   = "Dummy demod for DVB-T/T2/C/S/S2",
+			.frequency_min_hz       = 51 * MHz,
+			.frequency_max_hz       = 2150 * MHz,
+			.frequency_stepsize_hz  = 62500,
+			.frequency_tolerance_hz = 29500 * kHz,
+			.symbol_rate_min        = 1000000,
+			.symbol_rate_max        = 45000000,
+
+			.caps = FE_CAN_FEC_1_2 |
+				FE_CAN_FEC_2_3 |
+				FE_CAN_FEC_3_4 |
+				FE_CAN_FEC_4_5 |
+				FE_CAN_FEC_5_6 |
+				FE_CAN_FEC_6_7 |
+				FE_CAN_FEC_7_8 |
+				FE_CAN_FEC_8_9 |
+				FE_CAN_QAM_16 |
+				FE_CAN_QAM_64 |
+				FE_CAN_QAM_32 |
+				FE_CAN_QAM_128 |
+				FE_CAN_QAM_256 |
+				FE_CAN_QAM_AUTO |
+				FE_CAN_QPSK |
+				FE_CAN_FEC_AUTO |
+				FE_CAN_INVERSION_AUTO |
+				FE_CAN_TRANSMISSION_MODE_AUTO |
+				FE_CAN_GUARD_INTERVAL_AUTO |
+				FE_CAN_HIERARCHY_AUTO,
+		}
+
+		....
+
+For more information on dvb-fe-tools check its online documentation here:
+`dvb-fe-tool Documentation
+<https://www.linuxtv.org/wiki/index.php/Dvb-fe-tool>`_.
+
+Using dvb-scan
+~~~~~~~~~~~~~~
+
+In order to tune into a channel and read the PSI tables, we can use dvb-scan.
+
+For this, one should provide a configuration file known as a 'scan file',
+here's an example::
+
+	[Channel]
+	FREQUENCY = 474000000
+	MODULATION = QAM/AUTO
+	SYMBOL_RATE = 6940000
+	INNER_FEC = AUTO
+	DELIVERY_SYSTEM = DVBC/ANNEX_A
+
+.. note::
+	The parameters depend on the video standard you're testing.
+
+.. note::
+	Vidtv is a fake driver and does not validate much of the information
+	in the scan file. Just specifying 'FREQUENCY' and 'DELIVERY_SYSTEM'
+	should be enough for DVB-T/DVB-T2. For DVB-S/DVB-C however, you
+	should also provide 'SYMBOL_RATE'.
+
+You can browse scan tables online here: `dvb-scan-tables
+<https://git.linuxtv.org/dtv-scan-tables.git>`_.
+
+Assuming this channel is named 'channel.conf', you can then run::
+
+	$ dvbv5-scan channel.conf
+	dvbv5-scan ~/vidtv.conf
+	ERROR    command BANDWIDTH_HZ (5) not found during retrieve
+	Cannot calc frequency shift. Either bandwidth/symbol-rate is unavailable (yet).
+	Scanning frequency #1 330000000
+	    (0x00) Signal= -68.00dBm
+	Scanning frequency #2 474000000
+	Lock   (0x1f) Signal= -34.45dBm C/N= 33.74dB UCB= 0
+	Service Beethoven, provider LinuxTV.org: digital television
+
+For more information on dvb-scan, check its documentation online here:
+`dvb-scan Documentation <https://www.linuxtv.org/wiki/index.php/Dvbscan>`_.
+
+Using dvb-zap
+~~~~~~~~~~~~~
+
+dvbv5-zap is a command line tool that can be used to record MPEG-TS to disk. The
+typical use is to tune into a channel and put it into record mode. The example
+below - which is taken from the documentation - illustrates that\ [1]_::
+
+	$ dvbv5-zap -c dvb_channel.conf "beethoven" -o music.ts -P -t 10
+	using demux 'dvb0.demux0'
+	reading channels from file 'dvb_channel.conf'
+	tuning to 474000000 Hz
+	pass all PID's to TS
+	dvb_set_pesfilter 8192
+	dvb_dev_set_bufsize: buffer set to 6160384
+	Lock   (0x1f) Quality= Good Signal= -34.66dBm C/N= 33.41dB UCB= 0 postBER= 0 preBER= 1.05x10^-3 PER= 0
+	Lock   (0x1f) Quality= Good Signal= -34.57dBm C/N= 33.46dB UCB= 0 postBER= 0 preBER= 1.05x10^-3 PER= 0
+	Record to file 'music.ts' started
+	received 24587768 bytes (2401 Kbytes/sec)
+	Lock   (0x1f) Quality= Good Signal= -34.42dBm C/N= 33.89dB UCB= 0 postBER= 0 preBER= 2.44x10^-3 PER= 0
+
+.. [1] In this example, it records 10 seconds with all program ID's stored
+       at the music.ts file.
+
+
+The channel can be watched by playing the contents of the stream with some
+player that  recognizes the MPEG-TS format, such as ``mplayer`` or ``vlc``.
+
+By playing the contents of the stream one can visually inspect the workings of
+vidtv, e.g., to play a recorded TS file with::
+
+	$ mplayer music.ts
+
+or, alternatively, running this command on one terminal::
+
+	$ dvbv5-zap -c dvb_channel.conf "beethoven" -P -r &
+
+And, on a second terminal, playing the contents from DVR interface with::
+
+	$ mplayer /dev/dvb/adapter0/dvr0
+
+For more information on dvb-zap check its online documentation here:
+`dvb-zap Documentation
+<https://www.linuxtv.org/wiki/index.php/Dvbv5-zap>`_.
+See also: `zap <https://www.linuxtv.org/wiki/index.php/Zap>`_.
+
+
+What can still be improved in vidtv
+-----------------------------------
+
+Add *debugfs* integration
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Although frontend drivers provide DVBv5 statistics via the .read_status
+call, a nice addition would be to make additional statistics available to
+userspace via debugfs, which is a simple-to-use, RAM-based filesystem
+specifically designed for debug purposes.
+
+The logic for this would be implemented on a separate file so as not to
+pollute the frontend driver.  These statistics are driver-specific and can
+be useful during tests.
+
+The Siano driver is one example of a driver using
+debugfs to convey driver-specific statistics to userspace and it can be
+used as a reference.
+
+This should be further enabled and disabled via a Kconfig
+option for convenience.
+
+Add a way to test video
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Currently, vidtv can only encode PCM audio. It would be great to implement
+a barebones version of MPEG-2 video encoding so we can also test video. The
+first place to look into is *ISO 13818-2: Information technology — Generic
+coding of moving pictures and associated audio information — Part 2: Video*,
+which covers the encoding of compressed video in MPEG Transport Streams.
+
+This might optionally use the Video4Linux2 Test Pattern Generator, v4l2-tpg,
+which resides at::
+
+	drivers/media/common/v4l2-tpg/
+
+
+Add white noise simulation
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The vidtv tuner already has code to identify whether the chosen frequency
+is too far away from a table of valid frequencies. For now, this means that
+the demodulator can eventually lose the lock on the signal, since the tuner will
+report a bad signal quality.
+
+A nice addition is to simulate some noise when the signal quality is bad by:
+
+- Randomly dropping some TS packets. This will trigger a continuity error if the
+  continuity counter is updated but the packet is not passed on to the demux.
+
+- Updating the error statistics accordingly (e.g. BER, etc).
+
+- Simulating some noise in the encoded data.
+
+Functions and structs used within vidtv
+---------------------------------------
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_bridge.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_channel.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_demod.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_encoder.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_mux.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_pes.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_psi.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_s302m.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_ts.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_tuner.h
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_common.c
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_tuner.c