netdev - Re: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT valid

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Date:   Tue, 2 Feb 2021 08:37:25 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Joakim Zhang <qiangqing.zhang@....com>, linux-can@...r.kernel.org
Cc:     netdev@...r.kernel.org, linux-imx@....com
Subject: Re: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT
 valid

On 2/2/21 7:23 AM, Joakim Zhang wrote:
> RX FIFO enable failed could happen when do system reboot stress test,
> one customer reports failure rate is about 50%.
> 
> [    0.303958] flexcan 5a8d0000.can: 5a8d0000.can supply xceiver not found, using dummy regulator
> [    0.304281] flexcan 5a8d0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
> [    0.314640] flexcan 5a8d0000.can: registering netdev failed
> [    0.320728] flexcan 5a8e0000.can: 5a8e0000.can supply xceiver not found, using dummy regulator
> [    0.320991] flexcan 5a8e0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
> [    0.331360] flexcan 5a8e0000.can: registering netdev failed
> [    0.337444] flexcan 5a8f0000.can: 5a8f0000.can supply xceiver not found, using dummy regulator
> [    0.337716] flexcan 5a8f0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
> [    0.348117] flexcan 5a8f0000.can: registering netdev failed
> 
> RX FIFO should be enabled after the FRZ/HALT are valid. But the current
> code set RX FIFO enable and FRZ/HALT at the same time.
> 
> Fixes: e955cead03117 ("CAN: Add Flexcan CAN controller driver")
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> ---
>  drivers/net/can/flexcan.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index 038fe1036df2..8ee9fa2f4161 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -1803,6 +1803,7 @@ static int register_flexcandev(struct net_device *dev)
>  {
>  	struct flexcan_priv *priv = netdev_priv(dev);
>  	struct flexcan_regs __iomem *regs = priv->regs;
> +	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
>  	u32 reg, err;
>  
>  	err = flexcan_clks_enable(priv);
> @@ -1825,10 +1826,19 @@ static int register_flexcandev(struct net_device *dev)
>  	if (err)
>  		goto out_chip_disable;
>  
> -	/* set freeze, halt and activate FIFO, restrict register access */
> +	/* set freeze, halt and polling the freeze ack */
>  	reg = priv->read(&regs->mcr);
> -	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT |
> -		FLEXCAN_MCR_FEN | FLEXCAN_MCR_SUPV;
> +	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT;
> +	priv->write(reg, &regs->mcr);
> +
> +	while (timeout-- && !(priv->read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
> +		udelay(100);

Please make use of existing functions like flexcan_chip_freeze().

regards,
Marc

-- 
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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