Re: [PATCH v5 4/4] iplink_can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC)

On Mon. 16 août 2021 at 17:12, Marc Kleine-Budde [off-list ref] wrote:

On 14.08.2021 19:17:28, Vincent Mailhol wrote:

quoted

At high bit rates, the propagation delay from the TX pin to the RX pin
of the transceiver causes measurement errors: the sample point on the
RX pin might occur on the previous bit.

This issue is addressed in ISO 11898-1 section 11.3.3 "Transmitter
delay compensation" (TDC).

This patch brings command line support to nine TDC parameters which
were recently added to the kernel's CAN netlink interface in order to
implement TDC:
  - IFLA_CAN_TDC_TDCV_MIN: Transmitter Delay Compensation Value
    minimum value
  - IFLA_CAN_TDC_TDCV_MAX: Transmitter Delay Compensation Value
    maximum value
  - IFLA_CAN_TDC_TDCO_MIN: Transmitter Delay Compensation Offset
    minimum value
  - IFLA_CAN_TDC_TDCO_MAX: Transmitter Delay Compensation Offset
    maximum value
  - IFLA_CAN_TDC_TDCF_MIN: Transmitter Delay Compensation Filter
    window minimum value
  - IFLA_CAN_TDC_TDCF_MAX: Transmitter Delay Compensation Filter
    window maximum value
  - IFLA_CAN_TDC_TDCV: Transmitter Delay Compensation Value
  - IFLA_CAN_TDC_TDCO: Transmitter Delay Compensation Offset
  - IFLA_CAN_TDC_TDCF: Transmitter Delay Compensation Filter window

All those new parameters are nested together into the attribute
IFLA_CAN_TDC.

A tdc-mode parameter allow to specify how to operate. Valid options
are:

  * auto: the transmitter automatically measures TDCV. As such, TDCV
    values can not be manually provided. In this mode, the user must
    specify TDCO and may also specify TDCF if supported.

  * manual: Use the TDCV value provided by the user are used. In this

                           ^^^^^                      ^^^
                           singular                   plural

ACK. I fixed that broken grammar in my local branch. As commented
before, I will send the next version of the iproute series after
we agree on the kernel part (unless someone finds a major issue).

FYI, this is the fixed sentence:
  * manual: use a static TDCV provided by the user. In this mode, the
    user must specify both TDCV and TDCO and may also specify TDCF if
    supported.


Yours sincerely,
Vincent