RE: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD

[Joakim Zhang <qiangqing.zhang@xxxxxxx>]

> -----Original Message-----
> From: Michael Walle <michael@xxxxxxxx>
> Sent: 2020年6月30日 2:18
> To: linux-can@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Cc: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>; Marc Kleine-Budde
> <mkl@xxxxxxxxxxxxxx>; David S . Miller <davem@xxxxxxxxxxxxx>; Jakub
> Kicinski <kuba@xxxxxxxxxx>; Joakim Zhang <qiangqing.zhang@xxxxxxx>;
> dl-linux-imx <linux-imx@xxxxxxx>; Michael Walle <michael@xxxxxxxx>
> Subject: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD
> 
> Up until now, the controller used non-ISO CAN-FD mode, although it supports it.
> Add support for ISO mode, too. By default the hardware is in non-ISO mode and
> an enable bit has to be explicitly set.
> 
> Signed-off-by: Michael Walle <michael@xxxxxxxx>
> ---
>  drivers/net/can/flexcan.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index
> 183e094f8d66..a92d3cdf4195 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -94,6 +94,7 @@
>  #define FLEXCAN_CTRL2_MRP		BIT(18)
>  #define FLEXCAN_CTRL2_RRS		BIT(17)
>  #define FLEXCAN_CTRL2_EACEN		BIT(16)
> +#define FLEXCAN_CTRL2_ISOCANFDEN	BIT(12)
> 
>  /* FLEXCAN memory error control register (MECR) bits */
>  #define FLEXCAN_MECR_ECRWRDIS		BIT(31)
> @@ -1344,14 +1345,25 @@ static int flexcan_chip_start(struct net_device
> *dev)
>  	else
>  		reg_mcr |= FLEXCAN_MCR_SRX_DIS;
> 
> -	/* MCR - CAN-FD */
> -	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
> +	/* MCR, CTRL2
> +	 *
> +	 * CAN-FD mode
> +	 * ISO CAN-FD mode
> +	 */
> +	reg_ctrl2 = priv->read(&regs->ctrl2);
> +	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
>  		reg_mcr |= FLEXCAN_MCR_FDEN;
> -	else
> +		reg_ctrl2 |= FLEXCAN_CTRL2_ISOCANFDEN;
> +	} else {
>  		reg_mcr &= ~FLEXCAN_MCR_FDEN;
> +	}
> +
> +	if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
> +		reg_ctrl2 &= ~FLEXCAN_CTRL2_ISOCANFDEN;


Hi Michael,

ip link set can0 up type can bitrate 1000000 dbitrate 5000000 fd on
Above cmd can configure ISO CAN-FD.

However, if users want to configure NON-ISO CAN-FD, should use below cmd, what I did before.
ip link set can0 up type can bitrate 1000000 dbitrate 5000000 fd on fd-non-iso on

Marc may not satisfy with it, to be honest, this looks not good, had better configure like below to enable NON-ISO CAN-FD.
ip link set can0 up type can bitrate 1000000 dbitrate 5000000 fd-non-iso on

I haven't got any good ideas yet.

Best Regards,
Joakim Zhang
>  	netdev_dbg(dev, "%s: writing mcr=0x%08x", __func__, reg_mcr);
>  	priv->write(reg_mcr, &regs->mcr);
> +	priv->write(reg_ctrl2, &regs->ctrl2);
> 
>  	/* CTRL
>  	 *
> @@ -1952,6 +1964,7 @@ static int flexcan_probe(struct platform_device
> *pdev)
> 
>  	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SUPPORT_FD) {
>  		priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
> +		priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD_NON_ISO;
>  		priv->can.bittiming_const = &flexcan_fd_bittiming_const;
>  		priv->can.data_bittiming_const =
>  			&flexcan_fd_data_bittiming_const;
> --
> 2.20.1