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Date:   Tue, 3 Dec 2019 19:21:36 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Joakim Zhang <qiangqing.zhang@....com>,
        "sean@...nix.com" <sean@...nix.com>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
Cc:     dl-linux-imx <linux-imx@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH V2 3/4] can: flexcan: change the way of stop mode
 acknowledgment

On 11/27/19 6:56 AM, Joakim Zhang wrote:
> Stop mode is entered when Stop mode is requested at chip level and
> MCR[LPM_ACK] is asserted by the FlexCAN.
> 
> Double check with IP owner, should poll MCR[LPM_ACK] for stop mode
> acknowledgment, not the acknowledgment from chip level which is used
> for glitch filter.
> 
> Fixes: 5f186c257fa4(can: flexcan: fix stop mode acknowledgment)
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> ------
> ChangeLog:
> 	V1->V2: no change.
> ---
>  drivers/net/can/flexcan.c | 64 ++++++++++++++++++++-------------------
>  1 file changed, 33 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index 5d5ed28d3005..d178146b3da5 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -388,6 +388,34 @@ static struct flexcan_mb __iomem *flexcan_get_mb(const struct flexcan_priv *priv
>  		(&priv->regs->mb[bank][priv->mb_size * mb_index]);
>  }
>  
> +static int flexcan_enter_low_power_ack(struct flexcan_priv *priv)

nitpick: please call this flexcan_low_power_enter_ack()
> +{
> +	struct flexcan_regs __iomem *regs = priv->regs;
> +	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
> +
> +	while (timeout-- && !(priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> +		udelay(10);
> +
> +	if (!(priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> +		return -ETIMEDOUT;
> +
> +	return 0;
> +}
> +
> +static int flexcan_exit_low_power_ack(struct flexcan_priv *priv)

...and this one flexcan_low_power_exit_ack()

> +{
> +	struct flexcan_regs __iomem *regs = priv->regs;
> +	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
> +
> +	while (timeout-- && (priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> +		udelay(10);
> +
> +	if (priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK)
> +		return -ETIMEDOUT;
> +
> +	return 0;
> +}

Can you move split the creation of
flexcan_low_power_enter_ack()/flexcan_low_power_exit_ack() and use in
flexcan_chip_enable/disable() into one patch and the conversion of
flexcan_enter_stop_mode()/flexcan_exit_stop_mode() into another.

Marc

> +
>  static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> @@ -406,7 +434,6 @@ static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable)
>  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);
> @@ -418,35 +445,24 @@ static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
>  			   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;
> +	return flexcan_enter_low_power_ack(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;
> +	/* get stop acknowledgment */
> +	return flexcan_exit_low_power_ack(priv);
>  }
>  
>  static void flexcan_try_exit_stop_mode(struct flexcan_priv *priv)
> @@ -512,39 +528,25 @@ static inline int flexcan_transceiver_disable(const struct flexcan_priv *priv)
>  static int flexcan_chip_enable(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> -	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
>  	u32 reg;
>  
>  	reg = priv->read(&regs->mcr);
>  	reg &= ~FLEXCAN_MCR_MDIS;
>  	priv->write(reg, &regs->mcr);
>  
> -	while (timeout-- && (priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> -		udelay(10);
> -
> -	if (priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK)
> -		return -ETIMEDOUT;
> -
> -	return 0;
> +	return flexcan_exit_low_power_ack(priv);
>  }
>  
>  static int flexcan_chip_disable(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> -	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
>  	u32 reg;
>  
>  	reg = priv->read(&regs->mcr);
>  	reg |= FLEXCAN_MCR_MDIS;
>  	priv->write(reg, &regs->mcr);
>  
> -	while (timeout-- && !(priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> -		udelay(10);
> -
> -	if (!(priv->read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
> -		return -ETIMEDOUT;
> -
> -	return 0;
> +	return flexcan_enter_low_power_ack(priv);
>  }
>  
>  static int flexcan_chip_freeze(struct flexcan_priv *priv)
> 


-- 
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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