[BUG] Re: [net 3/6] can: flexcan: invoke flexcan_chip_freeze() to enter freeze mode

[Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>]

Hello Joakim, Marc,

On 01.03.21 12:20, Marc Kleine-Budde wrote:
> From: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> 
> Invoke flexcan_chip_freeze() to enter freeze mode, since need poll
> freeze mode acknowledge.
> 
> Fixes: e955cead03117 ("CAN: Add Flexcan CAN controller driver")
> Link: https://lore.kernel.org/r/20210218110037.16591-4-qiangqing.zhang@xxxxxxx
> Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> ---
>  drivers/net/can/flexcan.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index e66a51dbea0a..134c05757a3b 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -1480,10 +1480,13 @@ static int flexcan_chip_start(struct net_device *dev)
>  
>  	flexcan_set_bittiming(dev);
>  
> +	/* set freeze, halt */
> +	err = flexcan_chip_freeze(priv);
> +	if (err)
> +		goto out_chip_disable;

With v5.12-rc3, both my FlexCAN controllers on an i.MX6Q now divide by zero
on probe because priv->can.bittiming.bitrate == 0 inside of flexcan_chip_freeze.

Reverting this patch fixes it.

> +
>  	/* MCR
>  	 *
> -	 * enable freeze
> -	 * halt now
>  	 * only supervisor access
>  	 * enable warning int
>  	 * enable individual RX masking
> @@ -1492,9 +1495,8 @@ static int flexcan_chip_start(struct net_device *dev)
>  	 */
>  	reg_mcr = priv->read(&regs->mcr);
>  	reg_mcr &= ~FLEXCAN_MCR_MAXMB(0xff);
> -	reg_mcr |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT | FLEXCAN_MCR_SUPV |
> -		FLEXCAN_MCR_WRN_EN | FLEXCAN_MCR_IRMQ | FLEXCAN_MCR_IDAM_C |
> -		FLEXCAN_MCR_MAXMB(priv->tx_mb_idx);
> +	reg_mcr |= FLEXCAN_MCR_SUPV | FLEXCAN_MCR_WRN_EN | FLEXCAN_MCR_IRMQ |
> +		FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_MAXMB(priv->tx_mb_idx);
>  
>  	/* MCR
>  	 *
> 

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