[RFC PATCH 0/1] Documentation: networking: document CAN ISO-TP

[RFC PATCH 0/1] Documentation: networking: document CAN ISO-TP

[Francesco Valla]

While the in-kernel ISO-TP stack is fully functional and easy to use, no
documentation exists for it. This patch adds such documentation,
containing the very basics of the protocol, the APIs and a basic
example.

Sending as RFC because my experience with the stack is as user and not
as its developer, and also because it's my first kernel contribution.

Thank you,

Francesco

Francesco Valla (1):
  Documentation: networking: document CAN ISO-TP

 Documentation/networking/index.rst |   1 +
 Documentation/networking/isotp.rst | 347 +++++++++++++++++++++++++++++
 2 files changed, 348 insertions(+)
 create mode 100644 Documentation/networking/isotp.rst

-- 
2.44.0

[PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Francesco Valla]

Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
15765-2) stack.

Signed-off-by: Francesco Valla <valla.francesco@gmail.com>
---
 Documentation/networking/index.rst |   1 +
 Documentation/networking/isotp.rst | 347 +++++++++++++++++++++++++++++
 2 files changed, 348 insertions(+)
 create mode 100644 Documentation/networking/isotp.rst

diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index 473d72c36d61..ba22acfae389 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -19,6 +19,7 @@ Contents:
    caif/index
    ethtool-netlink
    ieee802154
+   isotp
    j1939
    kapi
    msg_zerocopy
diff --git a/Documentation/networking/isotp.rst b/Documentation/networking/isotp.rst
new file mode 100644
index 000000000000..d0c49fd1f5c9
--- /dev/null
+++ b/Documentation/networking/isotp.rst
@@ -0,0 +1,347 @@
+.. SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+
+====================
+ISO-TP (ISO 15765-2) Transport Protocol
+====================
+
+Overview
+=========================
+
+ISO-TP, also known as ISO 15765-2 from the ISO standard it is defined in, is a
+transport protocol specifically defined for diagnostic communication on CAN.
+It is widely used in the automotive industry, for example as the transport
+protocol for UDSonCAN (ISO 14229-3) or emission-related diagnostic services
+(ISO 15031-5).
+
+ISO-TP can be used both on classical (2.0B) CAN and CAN-FD based networks.
+It is also designed to be compatible with a CAN network using SAE J1939 as data
+link layer (however, this is not a requirement).
+
+Addressing
+----------
+
+In its simplest form, ISO-TP is based on two kinds of addresses for the nodes
+connected to the same network:
+
+- a physical address, which identifies a single node and is used in 1-to-1
+  communication
+- a functional addess, which identifies a group of nodes and is used in 1-to-N
+  communication
+
+In a so-called "normal" addressing scenario, both these addresses are
+represented by a single byte and can be inserted inside the 29-bit version of
+the CAN ID. However, in order to support larger networks, an "extended"
+addressing scheme can be adopted; in this case, the first byte of the data
+payload is used as an additional component of the address (both for the
+physical and functional cases).
+
+Transport protocol and associated frame types
+---------------------------------------------
+
+When transmitting data using the ISO-TP protocol, the payload can either fit
+inside one single CAN message or not, also considering the overhead the protocol
+is generating and the optional extended addressing. In the first case, the data
+is transmitted at once using a so-called Single Frame (SF). In the second case,
+ISO-TP defines a multi-frame protocol, in which the sender asks (through a First
+Frame - FF) to the receiver the maximum supported size of a macro data block
+(``blocksize``) and the minimum time time between the single CAN messages
+composing such block (``stmin``). Once these informations have been received,
+the sender starts to send frames containing fragments of the data payload
+(called Consecutive Frames - CF), stopping after every ``blocksize``-sized block
+to wait confirmation from the receiver (which should then send a Flow Control
+frame - FC - to inform the sender about its availability to receive more data).
+
+Specifications used
+-------------------
+
+* ISO 15765-2 : Road vehicles - Diagnostic communication over Controller Area
+  Network (DoCAN). Part 2: Transport protocol and network layer services.
+
+How to Use ISO-TP
+=================
+
+As with others CAN protocols, the ISO-TP stack support is built as a variant of
+the SocketCAN communication, and thus uses the socket APIs.
+
+Creation and basic usage of an ISO-TP socket
+--------------------------------------------
+
+To use the ISO-TP stack, ``#include <linux/can/isotp.h>`` shall be used. A
+socket can then be created using the ``PF_CAN`` protocol family, the
+``SOCK_DGRAM`` type (as the underlying protocol is datagram-based by design)
+and the ``CAN_ISOTP`` protocol:
+
+.. code-block:: C
+
+    s = socket(PF_CAN, SOCK_DGRAM, CAN_ISOTP);
+
+After the socket has been successfully created, ``bind(2)`` shall be called to
+bind the socket to the desired CAN interface, either:
+
+* specifying at least one RX or TX address, as part of the sockaddr supplied
+  to the call itself, or
+* after specifying broadcast flags through socket option (explained below)
+
+Once bound to an interface, the socket can be read from and written to using
+the usual ``read(2)`` and ``write(2)`` system calls, as well as ``send(2)``,
+``sendmsg(2)``, ``recv(2)`` and ``recvmsg(2)``.
+Unlike raw SocketCAN sockets, only the data payload shall be specified in all
+these calls, as the CAN header is automatically filled by the ISO-TP stack
+using information supplied during socket creation. In the same way, the stack
+will use the transport mechanism when required (i.e., when the size of the data
+payload exceeds the MTU of the underlying CAN bus).
+
+The sockaddr structure used for SocketCAN has extensions for use with ISO-TP,
+as specified below:
+
+.. code-block:: C
+
+    struct sockaddr_can {
+        sa_family_t can_family;
+        int         can_ifindex;
+        union {
+            struct { canid_t rx_id, tx_id; } tp;
+        ...
+        } can_addr;
+    }
+
+* ``can_family`` and ``can_ifindex`` serve the same purpose as for other
+  SocketCAN sockets.
+
+* ``can_addr.tp.rx_id`` specifies the receive (RX) CAN ID and will be used as
+  a RX filter.
+
+* ``can_addr.tp.tx_id`` specifies the transmit (TX) CAN ID
+
+ISO-TP socket options
+---------------------
+
+When creating an ISO-TP socket, reasonable defaults are set. Some options can
+be modified with ``setsockopt(2)`` and/or read back with ``getsockopt(2)``.
+
+General options
+~~~~~~~~~~~~~~~
+
+General socket options can be passed using the ``CAN_ISOTP_OPTS`` optname:
+
+.. code-block:: C
+
+    struct can_isotp_options opts;
+    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_OPTS, &opts, sizeof(opts))
+
+where the ``can_isotp_options`` structure has the following contents:
+
+.. code-block:: C
+
+    struct can_isotp_options {
+        u32 flags;
+        u32 frame_txtime;
+        u8  ext_address;
+        u8  txpad_content;
+        u8  rxpad_content;
+        u8  rx_ext_address;
+    };
+
+* ``flags``: modifiers to be applied to the default behaviour of the ISO-TP
+  stack. Following flags are available:
+
+  - ``CAN_ISOTP_LISTEN_MODE``: listen only (do not send FC frames)
+  - ``CAN_ISOTP_EXTEND_ADDR``: enable extended addressing, using the byte
+    specified in ``ext_address`` as additional address byte.
+  - ``CAN_ISOTP_TX_PADDING``: enable padding for tranmsitted frames, using
+    ``txpad_content`` as value for the padding bytes.
+  - ``CAN_ISOTP_RX_PADDING``: enable padding for the received frames, using
+    ``rxpad_content`` as value for the padding bytes.
+  - ``CAN_ISOTP_CHK_PAD_LEN``: check for correct padding length on the received
+    frames.
+  - ``CAN_ISOTP_CHK_PAD_DATA``: check padding bytes on the received frames
+    against ``rxpad_content``; if ``CAN_ISOTP_RX_PADDING`` is not specified,
+    this flag is ignored.
+  - ``CAN_ISOTP_HALF_DUPLEX``: force ISO-TP socket in half duples mode
+    (that is, transport mechanism can only be incoming or outgoing at the same
+    time, not both)
+  - ``CAN_ISOTP_FORCE_TXSTMIN``: ignore stmin from received FC
+  - ``CAN_ISOTP_FORCE_RXSTMIN``: ignore CFs depending on rx stmin
+  - ``CAN_ISOTP_RX_EXT_ADDR``: use ``rx_ext_address`` instead of ``ext_address``
+    as extended addressing byte on the reception path.
+  - ``CAN_ISOTP_WAIT_TX_DONE``: wait until the frame is sent before returning
+    from ``write(2)`` and ``send(2)`` calls (i.e., blocking write operations).
+  - ``CAN_ISOTP_SF_BROADCAST``: use 1-to-N functional addressing (cannot be
+    specified alongside ``CAN_ISOTP_CF_BROADCAST``)
+  - ``CAN_ISOTP_CF_BROADCAST``: use 1-to-N transmission without flow control
+    (cannot be specified alongside ``CAN_ISOTP_SF_BROADCAST``)
+  - ``CAN_ISOTP_DYN_FC_PARMS``: enable dynamic update of flow control parameters
+
+* ``frame_txtime``: frame transmission time (defined as N_As/N_Ar inside the
+  ISO standard); if ``0``, the default (or the last set value) is used.
+  To set the transmission time to ``0``, the ``CAN_ISOTP_FRAME_TXTIME_ZERO``
+  macro (equal to 0xFFFFFFFF) shall be used.
+
+* ``ext_address``: extended addressing byte, used if the
+  ``CAN_ISOTP_EXTEND_ADDR`` flag is specified.
+
+* ``txpad_content``: byte used as padding value for transmitted frames
+
+* ``rxpad_content``: byte used as padding value for received frames
+
+* ``rx_ext_address``: extended addressing byte for the reception path, used if
+  the ``CAN_ISOTP_RX_EXT_ADDR`` flag is specified.
+
+Flow Control options
+~~~~~~~~~~~~~~~~~~~~
+
+Flow Control (FC) options can be passed using the ``CAN_ISOTP_RECV_FC`` optname:
+
+.. code-block:: C
+
+    struct can_isotp_fc_options fc_opts;
+    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_RECV_FC, &fc_opts, sizeof(fc_opts));
+
+where the ``can_isotp_fc_options`` structure has the following contents:
+
+.. code-block:: C
+
+    struct can_isotp_options {
+        u8 bs;
+        u8 stmin;
+        u8 wftmax;
+    };
+
+* ``bs``: blocksize provided in flow control frames.
+
+* ``stmin``: minimum separation time provided in flow control frames; can
+  have the following values (others are reserved):
+  - 0x00 - 0x7F : 0 - 127 ms
+  - 0xF1 - 0xF9 : 100 us - 900 us
+
+* ``wftmax``: maximum number of wait frames provided in flow control frames.
+
+Link Layer options
+~~~~~~~~~~~~~~~~~~
+
+Link Layer (LL) options can be passed using the ``CAN_ISOTP_LL_OPTS`` optname:
+
+.. code-block:: C
+
+    struct can_isotp_ll_options ll_opts;
+    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_LL_OPTS, &ll_opts, sizeof(ll_opts));
+
+where the ``can_isotp_ll_options`` structure has the following contents:
+
+.. code-block:: C
+
+    struct can_isotp_ll_options {
+        u8 mtu;
+        u8 tx_dl;
+        u8 tx_flags;
+    };
+
+* ``mtu``: generated and accepted CAN frame type, can be equal to ``CAN_MTU``
+  for classical CAN frames or ``CANFD_MTU`` for CAN FD frames.
+
+* ``tx_dl``: maximum payload length for transmitted frames, can have one value
+  among: 8, 12, 16, 20, 24, 32, 48, 64.
+
+* ``tx_flags``: flags set set into ``struct canfd_frame.flags`` at frame
+  creation.
+
+Transmission stmin
+~~~~~~~~~~~~~~~~~~
+
+The transmission minimum separaton time (stmin) can be forced using the
+``CAN_ISOTP_TX_STMIN`` optname and providing an stmin value in microseconds as
+a 32bit unsigned integer; this will overwrite the value sent by the receiver in
+flow control frames:
+
+.. code-block:: C
+
+    uint32_t stmin;
+    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_TX_STMIN, &stmin, sizeof(stmin));
+
+Reception stmin
+~~~~~~~~~~~~~~~
+
+The reception minimum separaton time (stmin) can be forced using the
+``CAN_ISOTP_RX_STMIN`` optname and providing an stmin value in microseconds as
+a 32bit unsigned integer; received Consecutive Frames (CF) which timestamps
+differ less than this value will be ignored:
+
+.. code-block:: C
+
+    uint32_t stmin;
+    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_RX_STMIN, &stmin, sizeof(stmin));
+
+Multi-frame transport support
+--------------------------
+
+The ISO-TP stack contained inside the Linux kernel supports the multi-frame
+transport mechanism defined by the standard, with the following contraints:
+
+* the maximum size of a PDU is defined by a module parameter, with an hard
+  limit imposed at build time
+* when a transmission is in progress, subsequent calls to ``write(2)`` will
+  block, while calls to ``send(2)`` will either block or fail depending on the
+  presence of the ``MSG_DONTWAIT`` flag
+* no support is present for sending "wait frames": wheter a PDU can be fully
+  received or not is decided when the First Frame is received
+
+Errors
+------
+
+Following errors are reported to userspace:
+
+RX path errors
+~~~~~~~~~~~~~~
+
+============ =================================================================
+-ETIMEDOUT   timeout of data reception
+-EILSEQ      sequence number mismatch during a multi-frame reception
+-EBADMSG     data reception with wrong padding
+============ =================================================================
+
+TX path errors
+~~~~~~~~~~~~~~
+
+========== =================================================================
+-ECOMM     flow control reception timeout
+-EMSGSIZE  flow control reception overflow
+-EBADMSG   flow control reception with wrong layout/padding
+========== =================================================================
+
+Examples
+========
+
+Basic node example
+------------------
+
+Following example implements a node using "normal" physical addressing, with
+RX ID equal to 0x18DAF142 and a TX ID equal to 0x18DA42F1. All options are left
+to their default.
+
+.. code-block:: C
+
+  int s;
+  struct sockaddr_can addr;
+  int ret;
+
+  s = socket(PF_CAN, SOCK_DGRAM, CAN_ISOTP);
+  if (s < 0)
+      exit(1);
+
+  addr.can_family = AF_CAN;
+  addr.can_ifindex = if_nametoindex("can0");
+  addr.tp.tx_id = 0x18DA42F1;
+  addr.tp.rx_id = 0x18DAF142;
+
+  ret = bind(s, (struct sockaddr *)&addr, sizeof(addr));
+  if (ret < 0)
+      exit(1);
+
+  // Data can now be received using read(s, ...) and sent using write(s, ...)
+
+Additional examples
+-------------------
+
+More complete (and complex) examples can be found inside the ``isotp*`` userland
+tools, distributed as part of the ``can-utils`` utilities at:
+https://github.com/linux-can/can-utils
-- 
2.44.0

Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 2260 bytes --]

Hello Francesco,

thanks for your contribution! I've some remarks to make it a valid rst
file.

On 13.03.2024 23:34:31, Francesco Valla wrote:
> Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
> 15765-2) stack.
> 
> Signed-off-by: Francesco Valla <valla.francesco@gmail.com>
> ---
>  Documentation/networking/index.rst |   1 +
>  Documentation/networking/isotp.rst | 347 +++++++++++++++++++++++++++++
>  2 files changed, 348 insertions(+)
>  create mode 100644 Documentation/networking/isotp.rst
> 
> diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
> index 473d72c36d61..ba22acfae389 100644
> --- a/Documentation/networking/index.rst
> +++ b/Documentation/networking/index.rst
> @@ -19,6 +19,7 @@ Contents:
>     caif/index
>     ethtool-netlink
>     ieee802154
> +   isotp
>     j1939
>     kapi
>     msg_zerocopy
> diff --git a/Documentation/networking/isotp.rst b/Documentation/networking/isotp.rst
> new file mode 100644
> index 000000000000..d0c49fd1f5c9
> --- /dev/null
> +++ b/Documentation/networking/isotp.rst
> @@ -0,0 +1,347 @@
> +.. SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +
> +====================
> +ISO-TP (ISO 15765-2) Transport Protocol
> +====================

Please make the "=" as long as the text it encloses.

> +
> +Overview
> +=========================

Same here

[...]

> +Reception stmin
> +~~~~~~~~~~~~~~~
> +
> +The reception minimum separaton time (stmin) can be forced using the
> +``CAN_ISOTP_RX_STMIN`` optname and providing an stmin value in microseconds as
> +a 32bit unsigned integer; received Consecutive Frames (CF) which timestamps
> +differ less than this value will be ignored:
> +
> +.. code-block:: C
> +
> +    uint32_t stmin;
> +    ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_RX_STMIN, &stmin, sizeof(stmin));
> +
> +Multi-frame transport support
> +--------------------------

same here

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Francesco Valla]

On Thu, Mar 14, 2024 at 12:20:10PM +0100, Marc Kleine-Budde wrote:
> Hello Francesco,
> 
> thanks for your contribution! I've some remarks to make it a valid rst
> file.
> 

I did a bit of rework on section titles just before sending and obviously
forgot to update the separators. Will do that in the v2 patch.

Thanks for the review!

Regards,
Francesco

Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Bagas Sanjaya]

[-- Attachment #1: Type: text/plain, Size: 3116 bytes --]

On Wed, Mar 13, 2024 at 11:34:31PM +0100, Francesco Valla wrote:
> Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
> 15765-2) stack.
> 
> Signed-off-by: Francesco Valla <valla.francesco@gmail.com>
> ---
>  Documentation/networking/index.rst |   1 +
>  Documentation/networking/isotp.rst | 347 +++++++++++++++++++++++++++++
>  2 files changed, 348 insertions(+)
>  create mode 100644 Documentation/networking/isotp.rst
> 
> diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
> index 473d72c36d61..ba22acfae389 100644
> --- a/Documentation/networking/index.rst
> +++ b/Documentation/networking/index.rst
> @@ -19,6 +19,7 @@ Contents:
>     caif/index
>     ethtool-netlink
>     ieee802154
> +   isotp
>     j1939
>     kapi
>     msg_zerocopy
> diff --git a/Documentation/networking/isotp.rst b/Documentation/networking/isotp.rst
> new file mode 100644
> index 000000000000..d0c49fd1f5c9
> --- /dev/null
> +++ b/Documentation/networking/isotp.rst
> @@ -0,0 +1,347 @@
> +.. SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +
> +====================
> +ISO-TP (ISO 15765-2) Transport Protocol
> +====================
> +
> +Overview
> +=========================
> +
<snipped>...
> +Multi-frame transport support
> +--------------------------
> +

htmldocs build reports new warnings:

/home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:3: WARNING: Title overline too short.

====================
ISO-TP (ISO 15765-2) Transport Protocol
====================
/home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:275: WARNING: Title underline too short.

Multi-frame transport support
--------------------------
/home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:275: WARNING: Title underline too short.

Multi-frame transport support
--------------------------

I have applied the fixup:

---- >8 ----
diff --git a/Documentation/networking/isotp.rst b/Documentation/networking/isotp.rst
index d0c49fd1f5c976..a104322ddb6c5e 100644
--- a/Documentation/networking/isotp.rst
+++ b/Documentation/networking/isotp.rst
@@ -1,11 +1,11 @@
 .. SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
 
-====================
+=======================================
 ISO-TP (ISO 15765-2) Transport Protocol
-====================
+=======================================
 
 Overview
-=========================
+========
 
 ISO-TP, also known as ISO 15765-2 from the ISO standard it is defined in, is a
 transport protocol specifically defined for diagnostic communication on CAN.
@@ -272,7 +272,7 @@ differ less than this value will be ignored:
     ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_RX_STMIN, &stmin, sizeof(stmin));
 
 Multi-frame transport support
---------------------------
+-----------------------------
 
 The ISO-TP stack contained inside the Linux kernel supports the multi-frame
 transport mechanism defined by the standard, with the following contraints:

Thanks.

-- 
An old man doll... just what I always wanted! - Clara

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Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Francesco Valla]

On Fri, Mar 15, 2024 at 11:55:04AM +0700, Bagas Sanjaya wrote:

<snip>
> 
> htmldocs build reports new warnings:
> 
> /home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:3: WARNING: Title overline too short.
> 
> ====================
> ISO-TP (ISO 15765-2) Transport Protocol
> ====================
> /home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:275: WARNING: Title underline too short.
> 
> Multi-frame transport support
> --------------------------
> /home/bagas/repo/linux-kernel/Documentation/networking/isotp.rst:275: WARNING: Title underline too short.
> 
> Multi-frame transport support
> --------------------------
> 
> I have applied the fixup:
> 
> ---- >8 ----
> diff --git a/Documentation/networking/isotp.rst b/Documentation/networking/isotp.rst
> index d0c49fd1f5c976..a104322ddb6c5e 100644
> --- a/Documentation/networking/isotp.rst
> +++ b/Documentation/networking/isotp.rst
> @@ -1,11 +1,11 @@
>  .. SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
>  
> -====================
> +=======================================
>  ISO-TP (ISO 15765-2) Transport Protocol
> -====================
> +=======================================
>  
>  Overview
> -=========================
> +========
>  
>  ISO-TP, also known as ISO 15765-2 from the ISO standard it is defined in, is a
>  transport protocol specifically defined for diagnostic communication on CAN.
> @@ -272,7 +272,7 @@ differ less than this value will be ignored:
>      ret = setsockopt(s, SOL_CAN_ISOTP, CAN_ISOTP_RX_STMIN, &stmin, sizeof(stmin));
>  
>  Multi-frame transport support
> ---------------------------
> +-----------------------------
>  
>  The ISO-TP stack contained inside the Linux kernel supports the multi-frame
>  transport mechanism defined by the standard, with the following contraints:
> 
> Thanks.
> 
> -- 
> An old man doll... just what I always wanted! - Clara

Thank you! Fixes (along with some rework) will be applied to the v2.

Regards,
Francesco

Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Simon Horman]

On Wed, Mar 13, 2024 at 11:34:31PM +0100, Francesco Valla wrote:
> Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
> 15765-2) stack.
> 
> Signed-off-by: Francesco Valla <valla.francesco@gmail.com>

Hi Francesco,

As it looks like there will be a v2 of this patchset
please consider running checkpatch.pl --codespell
and addressing the warnings it reports.

...

> +Transport protocol and associated frame types
> +---------------------------------------------
> +
> +When transmitting data using the ISO-TP protocol, the payload can either fit
> +inside one single CAN message or not, also considering the overhead the protocol
> +is generating and the optional extended addressing. In the first case, the data
> +is transmitted at once using a so-called Single Frame (SF). In the second case,
> +ISO-TP defines a multi-frame protocol, in which the sender asks (through a First
> +Frame - FF) to the receiver the maximum supported size of a macro data block
> +(``blocksize``) and the minimum time time between the single CAN messages
> +composing such block (``stmin``). Once these informations have been received,

nit: Once this information has

> +the sender starts to send frames containing fragments of the data payload
> +(called Consecutive Frames - CF), stopping after every ``blocksize``-sized block
> +to wait confirmation from the receiver (which should then send a Flow Control
> +frame - FC - to inform the sender about its availability to receive more data).
> +

...

Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Francesco Valla]

Hi Simon,

On Tue, Mar 19, 2024 at 12:06:25PM +0000, Simon Horman wrote:
> On Wed, Mar 13, 2024 at 11:34:31PM +0100, Francesco Valla wrote:
> > Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
> > 15765-2) stack.
> > 
> > Signed-off-by: Francesco Valla <valla.francesco@gmail.com>
> 
> Hi Francesco,
> 
> As it looks like there will be a v2 of this patchset
> please consider running checkpatch.pl --codespell
> and addressing the warnings it reports.
> 

Will do before v2, thanks for the suggestion.

> ...
> 
> > +Transport protocol and associated frame types
> > +---------------------------------------------
> > +
> > +When transmitting data using the ISO-TP protocol, the payload can either fit
> > +inside one single CAN message or not, also considering the overhead the protocol
> > +is generating and the optional extended addressing. In the first case, the data
> > +is transmitted at once using a so-called Single Frame (SF). In the second case,
> > +ISO-TP defines a multi-frame protocol, in which the sender asks (through a First
> > +Frame - FF) to the receiver the maximum supported size of a macro data block
> > +(``blocksize``) and the minimum time time between the single CAN messages
> > +composing such block (``stmin``). Once these informations have been received,
> 
> nit: Once this information has

I never grasped the usage of "information" in English, which is not my
first language. I'll make this correction here.

> 
> > +the sender starts to send frames containing fragments of the data payload
> > +(called Consecutive Frames - CF), stopping after every ``blocksize``-sized block
> > +to wait confirmation from the receiver (which should then send a Flow Control
> > +frame - FC - to inform the sender about its availability to receive more data).
> > +
> 
> ...

Thanks for the review!

Regards,
Francesco

Re: [PATCH 1/1] Documentation: networking: document CAN ISO-TP

[Simon Horman]

On Wed, Mar 20, 2024 at 11:35:05PM +0100, Francesco Valla wrote:
> 
> Hi Simon,
> 
> On Tue, Mar 19, 2024 at 12:06:25PM +0000, Simon Horman wrote:
> > On Wed, Mar 13, 2024 at 11:34:31PM +0100, Francesco Valla wrote:
> > > Document basic concepts, APIs and behaviour of the CAN ISO-TP (ISO
> > > 15765-2) stack.
> > > 
> > > Signed-off-by: Francesco Valla <valla.francesco@gmail.com>
> > 
> > Hi Francesco,
> > 
> > As it looks like there will be a v2 of this patchset
> > please consider running checkpatch.pl --codespell
> > and addressing the warnings it reports.
> > 
> 
> Will do before v2, thanks for the suggestion.
> 
> > ...
> > 
> > > +Transport protocol and associated frame types
> > > +---------------------------------------------
> > > +
> > > +When transmitting data using the ISO-TP protocol, the payload can either fit
> > > +inside one single CAN message or not, also considering the overhead the protocol
> > > +is generating and the optional extended addressing. In the first case, the data
> > > +is transmitted at once using a so-called Single Frame (SF). In the second case,
> > > +ISO-TP defines a multi-frame protocol, in which the sender asks (through a First
> > > +Frame - FF) to the receiver the maximum supported size of a macro data block
> > > +(``blocksize``) and the minimum time time between the single CAN messages
> > > +composing such block (``stmin``). Once these informations have been received,
> > 
> > nit: Once this information has
> 
> I never grasped the usage of "information" in English, which is not my
> first language. I'll make this correction here.

I can't explain it properly, but my basic understanding
is that in English information is non-countable and thus has no plural.
Water is another example of a non-countable noun.

> > > +the sender starts to send frames containing fragments of the data payload
> > > +(called Consecutive Frames - CF), stopping after every ``blocksize``-sized block
> > > +to wait confirmation from the receiver (which should then send a Flow Control
> > > +frame - FC - to inform the sender about its availability to receive more data).
> > > +
> > 
> > ...
> 
> Thanks for the review!
> 
> Regards,
> Francesco
>