linux-kernel - Re: [PATCH 1/2] can: D_CAN: perform a sofware reset on open

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Message-ID: <b30e9834-a324-ad97-2050-df9600a95347@pengutronix.de>
Date:   Tue, 1 Oct 2019 16:32:03 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Jeroen Hofstee <jhofstee@...tronenergy.com>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] can: D_CAN: perform a sofware reset on open

On 9/26/19 10:50 AM, Jeroen Hofstee wrote:
> When the C_CAN interface is closed it is put in power down mode, but
> does not reset the error counters / state. So reset the D_CAN on open,
> so the reported state and the actual state match.
> 
> According to [1], the C_CAN module doesn't have the software reset.
> 
> [1] http://www.bosch-semiconductors.com/media/ip_modules/pdf_2/c_can_fd8/users_manual_c_can_fd8_r210_1.pdf
> 
> Signed-off-by: Jeroen Hofstee <jhofstee@...tronenergy.com>
> ---
>  drivers/net/can/c_can/c_can.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> index 606b7d8ffe13..502a181d02e7 100644
> --- a/drivers/net/can/c_can/c_can.c
> +++ b/drivers/net/can/c_can/c_can.c
> @@ -52,6 +52,7 @@
>  #define CONTROL_EX_PDR		BIT(8)
>  
>  /* control register */
> +#define CONTROL_SWR		BIT(15)
>  #define CONTROL_TEST		BIT(7)
>  #define CONTROL_CCE		BIT(6)
>  #define CONTROL_DISABLE_AR	BIT(5)
> @@ -569,6 +570,26 @@ static void c_can_configure_msg_objects(struct net_device *dev)
>  				   IF_MCONT_RCV_EOB);
>  }
>  
> +static int software_reset(struct net_device *dev)

Please add the common prefix "c_can_" to the function

> +{
> +	struct c_can_priv *priv = netdev_priv(dev);
> +	int retry = 0;
> +
> +	if (priv->type != BOSCH_D_CAN)
> +		return 0;
> +
> +	priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_SWR | CONTROL_INIT);
> +	while (priv->read_reg(priv, C_CAN_CTRL_REG) & CONTROL_SWR) {
> +		msleep(20);
> +		if (retry++ > 100) {
> +			netdev_err(dev, "CCTRL: software reset failed\n");
> +			return -EIO;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * Configure C_CAN chip:
>   * - enable/disable auto-retransmission
> @@ -578,6 +599,11 @@ static void c_can_configure_msg_objects(struct net_device *dev)
>  static int c_can_chip_config(struct net_device *dev)
>  {
>  	struct c_can_priv *priv = netdev_priv(dev);
> +	int err;
> +
> +	err = software_reset(dev);
> +	if (err)
> +		return err;
>  
>  	/* enable automatic retransmission */
>  	priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_ENABLE_AR);
> 

Marc

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