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

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Message-ID: <c24b0982-13af-ecdd-c3a2-7ec62863483c@pengutronix.de>
Date:   Mon, 17 Jun 2019 14:57:31 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Joakim Zhang <qiangqing.zhang@....com>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
Cc:     dl-linux-imx <linux-imx@....com>,
        "wg@...ndegger.com" <wg@...ndegger.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] can: flexcan: fix stop mode acknowledgment

On 6/11/19 8:47 AM, Joakim Zhang wrote:
> 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>
> ---
>  drivers/net/can/flexcan.c | 47 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 39 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index e35083ff31ee..282dac1d8f5c 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -404,9 +404,11 @@ 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 timeout = FLEXCAN_TIMEOUT_US / 10;
> +	unsigned int ackval;
>  	u32 reg_mcr;
>  
>  	reg_mcr = priv->read(&regs->mcr);
> @@ -416,20 +418,48 @@ 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 */
> +	regmap_read(priv->stm.gpr, priv->stm.ack_gpr, &ackval);

Please make use of regmap_read_poll_timeout().

Marc

-- 
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