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

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Message-ID: <CAMZ6RqJiAO-snH0+NKi8=+xi9UnU3sJ+1Ze8qYL0qPwG4eRZVg@mail.gmail.com>
Date:   Mon, 16 Aug 2021 19:40:52 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        linux-can <linux-can@...r.kernel.org>,
        Stefan Mätje <stefan.maetje@....eu>,
        netdev <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: 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 <mkl@...gutronix.de> wrote:
> 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

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