Re: mcp251x can't drop the can0 Interface

[John Whitmore <arigead@gmail.com>]

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On Sat, Feb 08, 2014 at 06:10:29PM +0100, Marc Kleine-Budde wrote:
> On 02/07/2014 09:12 PM, John Whitmore wrote:
> > I guess you might say that I'm playing with an MCP2515 connected to a
> > RaspberryPi. I've got a problem which I've asked about on the RaspberryPi
> > forum but have never received an answer, so as a last resort I thought I'd try
> > here.
> > 
> > Basically I bring up the MCP2515 in listen mode at a certain baud rate. I
> > wanted to work on auto detetection of baud rate. So after listening for a
> > period of time at a certain baud rate I try to change the baud rate but I
> > can't do that with the linux mcp251x driver (I don't think it's the driver's
> > fault but have no idea whose it is). I've put in some debug statements
> > to see what happens when I execute "ifconfig can0 down" and basically the
> > interface goes down momentarily and then gets brough straight back up
> > again. So when I try to use the "ip" command to set the new baud rate I get an
> > error that the device is busy. 
> 
> Please add this patch to the driver:
> 
> -------->8-------->8-------->8-------->8-------->8-------->8-------->8--------
> diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
> index cdb9808..b1ea15c 100644
> --- a/drivers/net/can/mcp251x.c
> +++ b/drivers/net/can/mcp251x.c
> @@ -697,6 +697,8 @@ static int mcp251x_stop(struct net_device *net)
>         struct mcp251x_priv *priv = netdev_priv(net);
>         struct spi_device *spi = priv->spi;
> 
> +       dump_stack();
> +
>         close_candev(net);
> 
>         priv->force_quit = 1;
> @@ -941,6 +943,8 @@ static int mcp251x_open(struct net_device *net)
>         unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_FALLING;
>         int ret;
> 
> +       dump_stack();
> +
>         ret = open_candev(net);
>         if (ret) {
>                 dev_err(&spi->dev, "unable to set initial baudrate!\n");
> 
> -------->8-------->8-------->8-------->8-------->8-------->8-------->8--------
> 
> Then reproduce your problem, then send dmesg output.
> 

Sorry for the slight delay went from the RaspberryPi 3.6 Kernel to the 3.10 to
see if maybe the later version worked. I'm afraid neither worked.

John


> Marc
> 
> -- 
> Pengutronix e.K.                  | Marc Kleine-Budde           |
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