linux-kernel - Re: [PATCH] can: c_can: move runtime PM enable/disable to c_can

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Date:   Mon, 1 Mar 2021 16:08:40 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Tong Zhang <ztong0001@...il.com>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        YueHaibing <yuehaibing@...wei.com>,
        Zhang Qilong <zhangqilong3@...wei.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: c_can: move runtime PM enable/disable to
 c_can_platform

On 28.02.2021 23:15:48, Tong Zhang wrote:
> Currently doing modprobe c_can_pci will make kernel complain
> "Unbalanced pm_runtime_enable!", this is caused by pm_runtime_enable()
> called before pm is initialized in register_candev() and doing so will

I don't see where register_candev() is doing any pm related
initialization.

> also cause it to enable twice.

> This fix is similar to 227619c3ff7c, move those pm_enable/disable code to
> c_can_platform.

As I understand 227619c3ff7c ("can: m_can: move runtime PM
enable/disable to m_can_platform"), PCI devices automatically enable PM,
when the "PCI device is added".

Please clarify the above point, otherwise the code looks OK, small
nitpick inline:

> Signed-off-by: Tong Zhang <ztong0001@...il.com>
> ---
>  drivers/net/can/c_can/c_can.c          | 26 ++------------------------
>  drivers/net/can/c_can/c_can_platform.c |  6 +++++-
>  2 files changed, 7 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> index ef474bae47a1..04f783b3d9d3 100644
> --- a/drivers/net/can/c_can/c_can.c
> +++ b/drivers/net/can/c_can/c_can.c
> @@ -212,18 +212,6 @@ static const struct can_bittiming_const c_can_bittiming_const = {
>  	.brp_inc = 1,
>  };
>  
> -static inline void c_can_pm_runtime_enable(const struct c_can_priv *priv)
> -{
> -	if (priv->device)
> -		pm_runtime_enable(priv->device);
> -}
> -
> -static inline void c_can_pm_runtime_disable(const struct c_can_priv *priv)
> -{
> -	if (priv->device)
> -		pm_runtime_disable(priv->device);
> -}
> -
>  static inline void c_can_pm_runtime_get_sync(const struct c_can_priv *priv)
>  {
>  	if (priv->device)
> @@ -1335,7 +1323,6 @@ static const struct net_device_ops c_can_netdev_ops = {
>  
>  int register_c_can_dev(struct net_device *dev)
>  {
> -	struct c_can_priv *priv = netdev_priv(dev);
>  	int err;
>  
>  	/* Deactivate pins to prevent DRA7 DCAN IP from being
> @@ -1345,28 +1332,19 @@ int register_c_can_dev(struct net_device *dev)
>  	 */
>  	pinctrl_pm_select_sleep_state(dev->dev.parent);
>  
> -	c_can_pm_runtime_enable(priv);
> -
>  	dev->flags |= IFF_ECHO;	/* we support local echo */
>  	dev->netdev_ops = &c_can_netdev_ops;
>  
>  	err = register_candev(dev);
> -	if (err)
> -		c_can_pm_runtime_disable(priv);
> -	else
> -		devm_can_led_init(dev);
> -
> +	if (!err)
> +	  devm_can_led_init(dev);

Please indent with two tabs here.

regards,
Marc

-- 
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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