Merge tag 'docs-for-linus' of git://git.lwn.net/linux
Pull documentation update from Jon Corbet: "There is a nice new document from Neil on how pathname lookups work and some new CAN driver documentation. Beyond that, we have kernel-doc fixes, a bit more work to support reproducible builds, and the usual collection of small fixes" * tag 'docs-for-linus' of git://git.lwn.net/linux: (34 commits) Documentation: add new description of path-name lookup. Documentation/vm/slub.txt: document slabinfo-gnuplot.sh Doc: ABI/stable: Fix typo in ABI/stable doc: Clarify that nmi_watchdog param is for hardlockups Typo correction for description in gpio document. DocBook: Fix kernel-doc to be case-insensitive for private: kernel-docs.txt: update kernelnewbies reference Doc:kvm: Fix typo in Doc/virtual/kvm Documentation/Changes: Add bc in "Current Minimal Requirements" section Documentation/email-clients.txt: remove trailing whitespace DocBook: Use a fixed encoding for output MAINTAINERS: The docs tree has moved Docs/kernel-parameters: Add earlycon devicetree usage SubmittingPatches: make Subject examples match the de facto standard Documentation: gpio: mention that <function>-gpio has been deprecated Documentation: cgroups: just fix a few typos Documentation: Update kselftest.txt Documentation: DMA API: Be more explicit that nents is always the same Documentation: Update the default value of crashkernel low zram: update documentation ...
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Linus Torvalds
@@ -1018,25 +1018,34 @@ solution for a couple of reasons:
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$ ip link set can0 type can help
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Usage: ip link set DEVICE type can
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[ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
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[ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
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phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
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[ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
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[ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
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phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
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[ loopback { on | off } ]
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[ listen-only { on | off } ]
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[ triple-sampling { on | off } ]
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[ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] |
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[ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1
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dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]
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[ restart-ms TIME-MS ]
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[ restart ]
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[ loopback { on | off } ]
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[ listen-only { on | off } ]
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[ triple-sampling { on | off } ]
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[ one-shot { on | off } ]
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[ berr-reporting { on | off } ]
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[ fd { on | off } ]
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[ fd-non-iso { on | off } ]
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[ presume-ack { on | off } ]
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Where: BITRATE := { 1..1000000 }
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SAMPLE-POINT := { 0.000..0.999 }
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TQ := { NUMBER }
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PROP-SEG := { 1..8 }
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PHASE-SEG1 := { 1..8 }
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PHASE-SEG2 := { 1..8 }
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SJW := { 1..4 }
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RESTART-MS := { 0 | NUMBER }
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[ restart-ms TIME-MS ]
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[ restart ]
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Where: BITRATE := { 1..1000000 }
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SAMPLE-POINT := { 0.000..0.999 }
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TQ := { NUMBER }
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PROP-SEG := { 1..8 }
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PHASE-SEG1 := { 1..8 }
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PHASE-SEG2 := { 1..8 }
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SJW := { 1..4 }
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RESTART-MS := { 0 | NUMBER }
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- Display CAN device details and statistics:
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@@ -1178,7 +1187,55 @@ solution for a couple of reasons:
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The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
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N.B. CAN FD capable devices can also handle and send legacy CAN frames.
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FIXME: Add details about the CAN FD controller configuration when available.
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When configuring CAN FD capable CAN controllers an additional 'data' bitrate
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has to be set. This bitrate for the data phase of the CAN FD frame has to be
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at least the bitrate which was configured for the arbitration phase. This
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second bitrate is specified analogue to the first bitrate but the bitrate
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setting keywords for the 'data' bitrate start with 'd' e.g. dbitrate,
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dsample-point, dsjw or dtq and similar settings. When a data bitrate is set
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within the configuration process the controller option "fd on" can be
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specified to enable the CAN FD mode in the CAN controller. This controller
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option also switches the device MTU to 72 (CANFD_MTU).
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The first CAN FD specification presented as whitepaper at the International
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CAN Conference 2012 needed to be improved for data integrity reasons.
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Therefore two CAN FD implementations have to be distinguished today:
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- ISO compliant: The ISO 11898-1:2015 CAN FD implementation (default)
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- non-ISO compliant: The CAN FD implementation following the 2012 whitepaper
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Finally there are three types of CAN FD controllers:
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1. ISO compliant (fixed)
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2. non-ISO compliant (fixed, like the M_CAN IP core v3.0.1 in m_can.c)
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3. ISO/non-ISO CAN FD controllers (switchable, like the PEAK PCAN-USB FD)
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The current ISO/non-ISO mode is announced by the CAN controller driver via
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netlink and displayed by the 'ip' tool (controller option FD-NON-ISO).
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The ISO/non-ISO-mode can be altered by setting 'fd-non-iso {on|off}' for
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switchable CAN FD controllers only.
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Example configuring 500 kbit/s arbitration bitrate and 4 Mbit/s data bitrate:
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$ ip link set can0 up type can bitrate 500000 sample-point 0.75 \
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dbitrate 4000000 dsample-point 0.8 fd on
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$ ip -details link show can0
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5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UNKNOWN \
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mode DEFAULT group default qlen 10
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link/can promiscuity 0
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can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
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bitrate 500000 sample-point 0.750
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tq 50 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1
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pcan_usb_pro_fd: tseg1 1..64 tseg2 1..16 sjw 1..16 brp 1..1024 \
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brp-inc 1
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dbitrate 4000000 dsample-point 0.800
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dtq 12 dprop-seg 7 dphase-seg1 8 dphase-seg2 4 dsjw 1
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pcan_usb_pro_fd: dtseg1 1..16 dtseg2 1..8 dsjw 1..4 dbrp 1..1024 \
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dbrp-inc 1
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clock 80000000
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Example when 'fd-non-iso on' is added on this switchable CAN FD adapter:
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can <FD,FD-NON-ISO> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
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6.7 Supported CAN hardware
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