Re: [PATCH V2 4/5] can: flexcan: fix transition from and to freeze mode in chip_{,un}freeze

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 07/28/2014 08:34 AM, Matthias Klein wrote:
> From: Marc Kleine-Budde <mkl@pengutronix.de>
> 
> This patch factors out freeze and unfreeze of the CAN core into seperate
> functions. Experiments have shown that the transition from and to freeze mode
> may take several microseconds, especially the time entering the freeze mode
> depends on the current bitrate.
> 
> This patch adds a while loop which polls the Freeze Mode ACK bit (FRZ_ACK) that
> indicates a successfull mode change. If the function runs into a timeout a
> error value is returned.
> 
> Cc: linux-stable <stable@vger.kernel.org>
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> Signed-off-by: Matthias Klein <matthias.klein@optimeas.de>

This patch is already mainline, please make your series based on the
latest net-next/master tree.

Marc

> ---
>  drivers/net/can/flexcan.c | 60 ++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 49 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index f6f95ae..b77f1da 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -322,6 +322,44 @@ static int flexcan_chip_disable(struct flexcan_priv *priv)
>  	return 0;
>  }
>  
> +static int flexcan_chip_freeze(struct flexcan_priv *priv)
> +{
> +	struct flexcan_regs __iomem *regs = priv->base;
> +	unsigned int timeout = 1000 * 1000 * 10 / priv->can.bittiming.bitrate;
> +	u32 reg;
> +
> +	reg = flexcan_read(&regs->mcr);
> +	reg |= FLEXCAN_MCR_HALT;
> +	flexcan_write(reg, &regs->mcr);
> +
> +	while (timeout-- && !(flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
> +		usleep_range(100, 200);
> +
> +	if (!(flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
> +		return -ETIMEDOUT;
> +
> +	return 0;
> +}
> +
> +static int flexcan_chip_unfreeze(struct flexcan_priv *priv)
> +{
> +	struct flexcan_regs __iomem *regs = priv->base;
> +	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
> +	u32 reg;
> +
> +	reg = flexcan_read(&regs->mcr);
> +	reg &= ~FLEXCAN_MCR_HALT;
> +	flexcan_write(reg, &regs->mcr);
> +
> +	while (timeout-- && (flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
> +		usleep_range(10, 20);
> +
> +	if (flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK)
> +		return -ETIMEDOUT;
> +
> +	return 0;
> +}
> +
>  static int flexcan_get_berr_counter(const struct net_device *dev,
>  				    struct can_berr_counter *bec)
>  {
> @@ -776,7 +814,7 @@ static int flexcan_chip_start(struct net_device *dev)
>  		netdev_err(dev, "Failed to softreset can module (mcr=0x%08x)\n",
>  			   reg_mcr);
>  		err = -ENODEV;
> -		goto out;
> +		goto out_chip_disable;
>  	}
>  
>  	flexcan_set_bittiming(dev);
> @@ -846,12 +884,12 @@ static int flexcan_chip_start(struct net_device *dev)
>  
>  	err = flexcan_transceiver_enable(priv);
>  	if (err)
> -		goto out;
> +		goto out_chip_disable;
>  
>  	/* synchronize with the can bus */
> -	reg_mcr = flexcan_read(&regs->mcr);
> -	reg_mcr &= ~FLEXCAN_MCR_HALT;
> -	flexcan_write(reg_mcr, &regs->mcr);
> +	err = flexcan_chip_unfreeze(priv);
> +	if (err)
> +		goto out_transceiver_disable;
>  
>  	priv->can.state = CAN_STATE_ERROR_ACTIVE;
>  
> @@ -864,7 +902,9 @@ static int flexcan_chip_start(struct net_device *dev)
>  
>  	return 0;
>  
> - out:
> + out_transceiver_disable:
> +	flexcan_transceiver_disable(priv);
> + out_chip_disable:
>  	flexcan_chip_disable(priv);
>  	return err;
>  }
> @@ -879,12 +919,10 @@ static void flexcan_chip_stop(struct net_device *dev)
>  {
>  	struct flexcan_priv *priv = netdev_priv(dev);
>  	struct flexcan_regs __iomem *regs = priv->base;
> -	u32 reg;
>  
> -	/* Disable + halt module */
> -	reg = flexcan_read(&regs->mcr);
> -	reg |= FLEXCAN_MCR_MDIS | FLEXCAN_MCR_HALT;
> -	flexcan_write(reg, &regs->mcr);
> +	/* freeze + disable module */
> +	flexcan_chip_freeze(priv);
> +	flexcan_chip_disable(priv);
>  
>  	/* Disable all interrupts */
>  	flexcan_write(0, &regs->imask1);
> 


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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