netdev - Re: [PATCH v10 1/1] can: usb: etas_es58X: add support for ETAS ES58X CAN USB interfaces

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Date:   Thu, 14 Jan 2021 18:23:15 +0100
From:   Oliver Hartkopp <socketcan@...tkopp.net>
To:     Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        linux-can@...r.kernel.org
Cc:     Arunachalam Santhanam <arunachalam.santhanam@...bosch.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jimmy Assarsson <extja@...ser.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "open list : NETWORKING DRIVERS" <netdev@...r.kernel.org>
Subject: Re: [PATCH v10 1/1] can: usb: etas_es58X: add support for ETAS ES58X
 CAN USB interfaces

Hi Vincent,

On 12.01.21 14:05, Vincent Mailhol wrote:
> This driver supports the ES581.4, ES582.1 and ES584.1 interfaces from
> ETAS GmbH (https://www.etas.com/en/products/es58x.php).

(..)

> diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.c b/drivers/net/can/usb/etas_es58x/es58x_fd.c
> new file mode 100644
> index 000000000000..6b9534f23c96
> --- /dev/null
> +++ b/drivers/net/can/usb/etas_es58x/es58x_fd.c

(..)

> +static void es58x_fd_print_bittiming(struct net_device *netdev,
> +				     struct es58x_fd_bittiming
> +				     *es58x_fd_bittiming, char *type)
> +{
> +	netdev_vdbg(netdev, "bitrate %s    = %d\n", type,
> +		    le32_to_cpu(es58x_fd_bittiming->bitrate));
> +	netdev_vdbg(netdev, "tseg1 %s      = %d\n", type,
> +		    le16_to_cpu(es58x_fd_bittiming->tseg1));
> +	netdev_vdbg(netdev, "tseg2 %s      = %d\n", type,
> +		    le16_to_cpu(es58x_fd_bittiming->tseg2));
> +	netdev_vdbg(netdev, "brp %s        = %d\n", type,
> +		    le16_to_cpu(es58x_fd_bittiming->brp));
> +	netdev_vdbg(netdev, "sjw %s        = %d\n", type,
> +		    le16_to_cpu(es58x_fd_bittiming->sjw));
> +}

What is the reason for this code?

These values can be retrieved with the 'ip' tool and are probably 
interesting for development - but not in the final code.

> +
> +static void es58x_fd_print_conf(struct net_device *netdev,
> +				struct es58x_fd_tx_conf_msg *tx_conf_msg)
> +{
> +	es58x_fd_print_bittiming(netdev, &tx_conf_msg->nominal_bittiming,
> +				 "nominal");
> +	netdev_vdbg(netdev, "samples_per_bit    = %d\n",
> +		    tx_conf_msg->samples_per_bit);
> +	netdev_vdbg(netdev, "sync_edge          = %d\n",
> +		    tx_conf_msg->sync_edge);
> +	netdev_vdbg(netdev, "physical_layer     = %d\n",
> +		    tx_conf_msg->physical_layer);
> +	netdev_vdbg(netdev, "self_reception     = %d\n",
> +		    tx_conf_msg->self_reception_mode);
> +	netdev_vdbg(netdev, "ctrlmode           = %d\n", tx_conf_msg->ctrlmode);
> +	netdev_vdbg(netdev, "canfd_enabled      = %d\n",
> +		    tx_conf_msg->canfd_enabled);
> +	if (tx_conf_msg->canfd_enabled) {
> +		es58x_fd_print_bittiming(netdev,
> +					 &tx_conf_msg->data_bittiming, "data");
> +		netdev_vdbg(netdev,
> +			    "Transmitter Delay Compensation        = %d\n",
> +			    tx_conf_msg->tdc);
> +		netdev_vdbg(netdev,
> +			    "Transmitter Delay Compensation Offset = %d\n",
> +			    le16_to_cpu(tx_conf_msg->tdco));
> +		netdev_vdbg(netdev,
> +			    "Transmitter Delay Compensation Filter = %d\n",
> +			    le16_to_cpu(tx_conf_msg->tdcf));
> +	}
> +}

Same here.

Either the information can be retrieved with the 'ip' tool OR the are 
not necessary as set to some reasonable default anyway OR we should 
implement the functionality in the general CAN driver infrastructure.

Regards,
Oliver