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

[Joakim Zhang]

> -----Original Message-----
> From: Michael Walle <mich...@walle.cc>
> Sent: 2020年6月30日 2:18
> To: linux-...@vger.kernel.org; netdev@vger.kernel.org;
> linux-ker...@vger.kernel.org
> Cc: Wolfgang Grandegger <w...@grandegger.com>; Marc Kleine-Budde
> <m...@pengutronix.de>; David S . Miller <da...@davemloft.net>; Jakub
> Kicinski <k...@kernel.org>; Joakim Zhang <qiangqing.zh...@nxp.com>;
> dl-linux-imx <linux-...@nxp.com>; Michael Walle <mich...@walle.cc>
> 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 <mich...@walle.cc>
> ---
>  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