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Date:   Fri, 18 Jun 2021 11:34:24 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc:     linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Oliver Hartkopp <socketcan@hartkopp.net>
Subject: Re: [PATCH v2 2/2] can: netlink: add interface for CAN-FD
 Transmitter Delay Compensation (TDC)
Message-ID: <20210618093424.xohvsqaaq5qf2bjn@pengutronix.de>
References: <20210603151550.140727-1-mailhol.vincent@wanadoo.fr>
 <20210603151550.140727-3-mailhol.vincent@wanadoo.fr>
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On 04.06.2021 00:15:50, Vincent Mailhol wrote:
> Add the netlink interface for TDC parameters of struct can_tdc_const
> and can_tdc.
>=20
> Contrary to the can_bittiming(_const) structures for which there is
> just a single IFLA_CAN(_DATA)_BITTMING(_CONST) entry per structure,
> here, we create a nested entry IFLA_CAN_TDC. Within this nested entry,
> additional IFLA_CAN_TDC_TDC* entries are added for each of the TDC
> parameters of the newly introduced struct can_tdc_const and struct
> can_tdc.
>=20
> For struct can_tdc_const, these are:
>         IFLA_CAN_TDC_TDCV_MAX
>         IFLA_CAN_TDC_TDCO_MAX
>         IFLA_CAN_TDC_TDCF_MAX
>=20
> For struct can_tdc, these are:
>         IFLA_CAN_TDC_TDCV
>         IFLA_CAN_TDC_TDCO
>         IFLA_CAN_TDC_TDCF

I just noticed in the mcp2518fd data sheet:

| bit 14-8 TDCO[6:0]: Transmitter Delay Compensation Offset bits;
| Secondary Sample Point (SSP) Two=E2=80=99s complement; offset can be posi=
tive,
| zero, or negative.
|=20
| 011 1111 =3D 63 x TSYSCLK
| ...
| 000 0000 =3D 0 x TSYSCLK
| ...
| 111 1111 =3D =E2=80=9364 x TSYSCLK

Have you takes this into account?

regards,
Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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