linux-kernel - Re: [PATCH v3 3/9] can: m_can: Map WoL to device_set_wakeup

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Message-ID: <20241011185929.GA53629@kernel.org>
Date: Fri, 11 Oct 2024 19:59:29 +0100
From: Simon Horman <horms@...nel.org>
To: Markus Schneider-Pargmann <msp@...libre.com>
Cc: Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	Vincent Mailhol <mailhol.vincent@...adoo.fr>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Nishanth Menon <nm@...com>,
	Vignesh Raghavendra <vigneshr@...com>,
	Tero Kristo <kristo@...nel.org>, linux-can@...r.kernel.org,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Matthias Schiffer <matthias.schiffer@...tq-group.com>,
	Vishal Mahaveer <vishalm@...com>,
	Kevin Hilman <khilman@...libre.com>, Dhruva Gole <d-gole@...com>,
	Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v3 3/9] can: m_can: Map WoL to device_set_wakeup_enable

On Fri, Oct 11, 2024 at 03:16:40PM +0200, Markus Schneider-Pargmann wrote:
> In some devices the pins of the m_can module can act as a wakeup source.
> This patch helps do that by connecting the PHY_WAKE WoL option to
> device_set_wakeup_enable. By marking this device as being wakeup
> enabled, this setting can be used by platform code to decide which
> sleep or poweroff mode to use.
> 
> Also this prepares the driver for the next patch in which the pinctrl
> settings are changed depending on the desired wakeup source.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
> ---
>  drivers/net/can/m_can/m_can.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index a978b960f1f1e1e8273216ff330ab789d0fd6d51..29accadc20de7e9efa509f14209cc62e599f03bb 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -2185,6 +2185,36 @@ static int m_can_set_coalesce(struct net_device *dev,
>  	return 0;
>  }
>  
> +static void m_can_get_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
> +{
> +	struct m_can_classdev *cdev = netdev_priv(dev);
> +
> +	wol->supported = device_can_wakeup(cdev->dev) ? WAKE_PHY : 0;
> +	wol->wolopts = device_may_wakeup(cdev->dev) ? WAKE_PHY : 0;
> +}
> +
> +static int m_can_set_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
> +{
> +	struct m_can_classdev *cdev = netdev_priv(dev);
> +	bool wol_enable = !!wol->wolopts & WAKE_PHY;

Hi Markus,

I suspect there is an order of operations issue here.
Should the line above be like this?

	bool wol_enable = !!(wol->wolopts & WAKE_PHY);

> +	int ret;
> +
> +	if ((wol->wolopts & WAKE_PHY) != wol->wolopts)
> +		return -EINVAL;
> +
> +	if (wol_enable == device_may_wakeup(cdev->dev))
> +		return 0;
> +
> +	ret = device_set_wakeup_enable(cdev->dev, wol_enable);
> +	if (ret) {
> +		netdev_err(cdev->net, "Failed to set wakeup enable %pE\n",
> +			   ERR_PTR(ret));
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +

...