Re: [PATCH net-next v3] net: dsa: mv88e6xxx: Prevent suspend to RAM

[Vivien Didelot]

Hi Miquel,

On Tue,  5 Feb 2019 12:07:28 +0100, Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:

> +/* There is no suspend to RAM support at DSA level yet, the switch configuration
> + * would be lost after a power cycle so prevent it to be suspended.
> + */
> +static int __maybe_unused mv88e6xxx_suspend(struct device *dev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int __maybe_unused mv88e6xxx_resume(struct device *dev)
> +{
> +	return 0;
> +}

The code looks good but my only concern is -EOPNOTSUPP. In this
context this code is specific to callbacks targeting bridge and
switchdev, while the dev_pm_ops are completely parallel to DSA.

It is intuitive but given Documentation/power/runtime_pm.txt, this
will default to being interpreted as a fatal error, while -EBUSY
seems to keep the device in an 'active' state in a saner way.

I don't understand yet how to properly tell PM core that suspend to RAM
isn't supported. If an error code different from -EAGAIN or -EBUSY
is the way to go, I'm good with it:

Reviewed-by: Vivien Didelot <vivien.didelot@xxxxxxxxx>


Thanks,

	Vivien