Re: [PATCH net-next 0/5] net: dsa: Multi-CPU ground work

On 06/06/2017 11:25 AM, Vivien Didelot wrote:

Hi Florian,

Florian Fainelli [off-list ref] writes:

quoted

This patch series prepares the ground for adding mutliple CPU port support to

                                                   multiple
                                                   

quoted

DSA, and starts by removing redundant pieces of information such as
master_netdev which is cpu_dp->ethernet. Finally drivers are moved away from

                         cpu_dp->netdev
                         

quoted

directly accessing ds->dst->cpu_dp and use appropriate helper functions.

Note that if you have Device Tree blobs/platform configurations that are
currently listing multiple CPU ports, the proposed behavior in
dsa_ds_get_cpu_dp() will be to return the last bit set in ds->cpu_port_mask.

Future plans include:
- making dst->cpu_dp a flexible data structure (array, list, you name it)
- having the ability for drivers to return a default/preferred CPU port (if
  necessary)

The overall patchset looks good. I have questions for future work
though.

I am still not sure that we need CPU port references in
dsa_switch_tree. When device tree or pdata is parsed, we have allocated
dsa_switch and dsa_port structures. We should be able validate and
assign all ds->ports[x].cpu_dp, before setting up the switches and
creating the slave devices. What do you think?

True, we should be able to do that, thanks for the suggestion.

Also I see dsa_ptr becoming a pointer to the assosicated dsa_port, and
dsa_port should contain the tagging ops for quick access. That is more
rigourous with the physical representation and much easier for
transparent multi-CPU port support.

Ultimately, I agree we should probably have dev->dsa_ptr be the actual
CPU port within the switch, and from the switch be able to go to the
collection of switches (dst). This should indeed be a bit more optimized
as there should be less traversal of structures in such a case.

Thanks!
-- 
Florian