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

Marc Kleine-Budde
2021-08-16T08:12:18Z

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On 14.08.2021 19:17:28, Vincent Mailhol wrote:
> 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
> mode, the user must specify both TDCV and TDCO and may also
> specify TDCF if supported.
>

Marc

--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
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