Re: [RFC PATCH] software node: Skip duplicated software_node sysfs

Qian Cai
2021-11-16T03:55:02Z

On Fri, Nov 05, 2021 at 09:39:42PM +0200, Andy Shevchenko wrote:
> > Anyway, what's the "upper layer"? Is that "struct device" or "struct
> > swnode"? I suppose you meant:
>
> struct device here.
>
> > - Remove "secondary" field from "struct fwnode_handle".
> > - Replace "fwnode" from "upper layer" with
> > "struct list_head fwnode_head;".
> > - Modify all functions in "software_node_ops" to use "fwnode_head".
> >
> > Is that correct?
>
> Yes.
>
> It might be a bit complicated taking into account how much fwnode is
> spreaded in the kernel... Basically, you need to fix all direct
> accesses to the dev->fwnode first.
> Besides that you need to check that fwnode, which is used out of the
> device scope, like in IRQ domains, doesn't use secondary pointer(s).
>
> This nevertheless adds a lot of flexibility and we may add whatever
> type of fwnodes and mix them together.

Okay, here is my plan until someone still has an idea to avoid a
redesign.

Frist, fixes all dev->fwnode / dev.fwnode to use dev_fwnode(). This
could be a standalone tree-wide patchset going out to avoid
heavy-lifting later.

Then, we can create another patchset on top. I have audited
"irq_domain" but not seen any "secondary" leakage. Struct
"cht_int33fe_data" does have some need to fix.

Rename set_secondary_fwnode() to insert_secondary_fwnode(). Fix things
in drivers/base/core.c, swnode.c etc to use the new fwnode_head and
anything I can't think of right now.

Since we will have multiple "software_node" (secondary fwnode:s) for a
single "device". What would be the usual way to deal with a
linked-list in the sysfs? I can think of just let "software_node"
become a directory to host a list of symlinks named from
swnode->id. Thoughts?