netdev - RE: [PATCH V4] can: flexcan: fix stop mode acknowledgment

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Date:   Mon, 22 Jul 2019 08:28:03 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     "mkl@...gutronix.de" <mkl@...gutronix.de>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC:     "wg@...ndegger.com" <wg@...ndegger.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V4] can: flexcan: fix stop mode acknowledgment


Kindly Ping...

Best Regards,
Joakim Zhang

> -----Original Message-----
> From: Joakim Zhang
> Sent: 2019年7月2日 9:46
> To: mkl@...gutronix.de; linux-can@...r.kernel.org
> Cc: wg@...ndegger.com; netdev@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>; Joakim Zhang <qiangqing.zhang@....com>
> Subject: [PATCH V4] can: flexcan: fix stop mode acknowledgment
> 
> To enter stop mode, the CPU should manually assert a global Stop Mode
> request and check the acknowledgment asserted by FlexCAN. The CPU must
> only consider the FlexCAN in stop mode when both request and
> acknowledgment conditions are satisfied.
> 
> Fixes: de3578c198c6 ("can: flexcan: add self wakeup support")
> Reported-by: Marc Kleine-Budde <mkl@...gutronix.de>
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> 
> ChangeLog:
> V1->V2:
> 	* regmap_read()-->regmap_read_poll_timeout()
> V2->V3:
> 	* change the way of error return, it will make easy for function
> 	extension.
> V3->V4:
> 	* rebase to linux-next/master, as this is a fix.
> ---
>  drivers/net/can/flexcan.c | 31 +++++++++++++++++++++++++++----
>  1 file changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index
> 1c66fb2ad76b..bf1bd6f5dbb1 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -400,9 +400,10 @@ static void flexcan_enable_wakeup_irq(struct
> flexcan_priv *priv, bool enable)
>  	priv->write(reg_mcr, &regs->mcr);
>  }
> 
> -static inline void flexcan_enter_stop_mode(struct flexcan_priv *priv)
> +static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> +	unsigned int ackval;
>  	u32 reg_mcr;
> 
>  	reg_mcr = priv->read(&regs->mcr);
> @@ -412,20 +413,37 @@ static inline void flexcan_enter_stop_mode(struct
> flexcan_priv *priv)
>  	/* enable stop request */
>  	regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
>  			   1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
> +
> +	/* get stop acknowledgment */
> +	if (regmap_read_poll_timeout(priv->stm.gpr, priv->stm.ack_gpr,
> +				     ackval, ackval & (1 << priv->stm.ack_bit),
> +				     0, FLEXCAN_TIMEOUT_US))
> +		return -ETIMEDOUT;
> +
> +	return 0;
>  }
> 
> -static inline void flexcan_exit_stop_mode(struct flexcan_priv *priv)
> +static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> +	unsigned int ackval;
>  	u32 reg_mcr;
> 
>  	/* remove stop request */
>  	regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
>  			   1 << priv->stm.req_bit, 0);
> 
> +	/* get stop acknowledgment */
> +	if (regmap_read_poll_timeout(priv->stm.gpr, priv->stm.ack_gpr,
> +				     ackval, !(ackval & (1 << priv->stm.ack_bit)),
> +				     0, FLEXCAN_TIMEOUT_US))
> +		return -ETIMEDOUT;
> +
>  	reg_mcr = priv->read(&regs->mcr);
>  	reg_mcr &= ~FLEXCAN_MCR_SLF_WAK;
>  	priv->write(reg_mcr, &regs->mcr);
> +
> +	return 0;
>  }
> 
>  static inline void flexcan_error_irq_enable(const struct flexcan_priv *priv)
> @@ -1615,7 +1633,9 @@ static int __maybe_unused flexcan_suspend(struct
> device *device)
>  		 */
>  		if (device_may_wakeup(device)) {
>  			enable_irq_wake(dev->irq);
> -			flexcan_enter_stop_mode(priv);
> +			err = flexcan_enter_stop_mode(priv);
> +			if (err)
> +				return err;
>  		} else {
>  			err = flexcan_chip_disable(priv);
>  			if (err)
> @@ -1665,10 +1685,13 @@ static int __maybe_unused
> flexcan_noirq_resume(struct device *device)  {
>  	struct net_device *dev = dev_get_drvdata(device);
>  	struct flexcan_priv *priv = netdev_priv(dev);
> +	int err;
> 
>  	if (netif_running(dev) && device_may_wakeup(device)) {
>  		flexcan_enable_wakeup_irq(priv, false);
> -		flexcan_exit_stop_mode(priv);
> +		err = flexcan_exit_stop_mode(priv);
> +		if (err)
> +			return err;
>  	}
> 
>  	return 0;
> --
> 2.17.1