Re: [net-next PATCH v4 03/11] net: pcs: Add subsystem

[Sean Anderson <sean.anderson@linux.dev>]

On 5/21/25 08:50, Lei Wei wrote:
> 
> 
> On 5/20/2025 1:43 AM, Sean Anderson wrote:
>> On 5/14/25 12:22, Lei Wei wrote:
>>>
>>>
>>> On 5/13/2025 12:10 AM, Sean Anderson wrote:
>>>> +/**
>>>> + * pcs_register_full() - register a new PCS
>>>> + * @dev: The device requesting the PCS
>>>> + * @fwnode: The PCS's firmware node; typically @dev.fwnode
>>>> + * @pcs: The PCS to register
>>>> + *
>>>> + * Registers a new PCS which can be attached to a phylink.
>>>> + *
>>>> + * Return: 0 on success, or -errno on error
>>>> + */
>>>> +int pcs_register_full(struct device *dev, struct fwnode_handle *fwnode,
>>>> +              struct phylink_pcs *pcs)
>>>> +{
>>>> +    struct pcs_wrapper *wrapper;
>>>> +
>>>> +    if (!dev || !pcs->ops)
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (!pcs->ops->pcs_an_restart || !pcs->ops->pcs_config ||
>>>> +        !pcs->ops->pcs_get_state)
>>>> +        return -EINVAL;
>>>> +
>>>> +    wrapper = kzalloc(sizeof(*wrapper), GFP_KERNEL);
>>>> +    if (!wrapper)
>>>> +        return -ENOMEM;
>>>
>>> How about the case where pcs is removed and then comes back again? Should we find the original wrapper and attach it to pcs again instead of creating a new wrapper?
>>
>> When the PCS is removed the old wrapper is removed from pcs_wrappers, so
>> it can no longer be looked up any more. I think trying to save/restore
>> the wrapper would be much more trouble than it's worth.
>>
> 
> In the case where Ethernet is not removed but PCS is removed and then
> comes back (when the sysfs unbind followed by bind method is used),
> it will not work because the Ethernet probe will not be initiated again, to call "pcs_get" again to obtain the new wrapper, it would still hold the old wrapper.

Correct. You must then unbind/bind the MAC.

--Sean