linux-kernel - Re: [PATCH can-next v2 1/3] can: m

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Message-ID: <ijxrgzolqpnnlpgzt22lparoeuqznqxz77ryx7o6tfzc7owp7h@n46bsemyqdxc>
Date: Mon, 18 Nov 2024 09:37:58 +0100
From: Sean Nyekjaer <sean@...nix.com>
To: Vincent Mailhol <mailhol.vincent@...adoo.fr>
Cc: Chandrasekar Ramakrishnan <rcsekar@...sung.com>, 
	Marc Kleine-Budde <mkl@...gutronix.de>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, linux-can@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH can-next v2 1/3] can: m_can: add deinit callback

On Fri, Nov 15, 2024 at 11:23:49PM +0100, Vincent Mailhol wrote:
> On 15/11/2024 at 17:15, Sean Nyekjaer wrote:
> > This is added in preparation for calling standby mode in the tcan4x5x
> > driver or other users of m_can.
> > For the tcan4x5x; If Vsup 12V, standby mode will save 7-8mA, when the
> > interface is down.
> > 
> > Signed-off-by: Sean Nyekjaer <sean@...nix.com>
> > ---
> >  drivers/net/can/m_can/m_can.c | 10 +++++++---
> >  drivers/net/can/m_can/m_can.h |  1 +
> >  2 files changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> > index a7b3bc439ae596527493a73d62b4b7a120ae4e49..667c70f8dc5e7e8b15b667119b63dea1fe667e8a 100644
> > --- a/drivers/net/can/m_can/m_can.c
> > +++ b/drivers/net/can/m_can/m_can.c
> > @@ -1750,12 +1750,16 @@ static void m_can_stop(struct net_device *dev)
> >  
> >  	/* Set init mode to disengage from the network */
> >  	ret = m_can_cccr_update_bits(cdev, CCCR_INIT, CCCR_INIT);
> > -	if (ret)
> > -		netdev_err(dev, "failed to enter standby mode: %pe\n",
> > -			   ERR_PTR(ret));
> >  
> >  	/* set the state as STOPPED */
> >  	cdev->can.state = CAN_STATE_STOPPED;
> > +
> > +	if (!ret && cdev->ops->deinit)
> > +		ret = cdev->ops->deinit(cdev);
> 
> Question: is there a reason not to try to deinit() even if the
> m_can_cccr_update_bits() failed?

Good question.
If the call the m_can core fails, then there bigger problems than setting
the (in nmy case) tcan4x5x in standby mode.

> 
> > +	if (ret)
> > +		netdev_err(dev, "failed to enter standby mode: %pe\n",
> > +			   ERR_PTR(ret));>  }
> >  
> >  static int m_can_close(struct net_device *dev)
> > diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> > index 92b2bd8628e6b31370f4accbc2e28f3b2257a71d..6206535341a22a68d7c5570f619e6c4d05e6fcf4 100644
> > --- a/drivers/net/can/m_can/m_can.h
> > +++ b/drivers/net/can/m_can/m_can.h
> > @@ -68,6 +68,7 @@ struct m_can_ops {
> >  	int (*write_fifo)(struct m_can_classdev *cdev, int addr_offset,
> >  			  const void *val, size_t val_count);
> >  	int (*init)(struct m_can_classdev *cdev);
> > +	int (*deinit)(struct m_can_classdev *cdev);
> >  };
> >  
> >  struct m_can_tx_op {
> > 
> 
> Yours sincerely,
> Vincent Mailhol
> 

/Sean