linux-kernel - Re: [RFC PATCH] software node: Skip duplicated software

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Message-ID: <52df4a97-1132-d594-0180-132d0ca714d5@quicinc.com>
Date:   Fri, 5 Nov 2021 14:47:43 -0400
From:   Qian Cai <quic_qiancai@...cinc.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] software node: Skip duplicated software_node sysfs



On 11/1/21 7:51 PM, Andy Shevchenko wrote:
> No, it’s not so easy. What you are doing is a papering over the real issue
> which is the limitation of the firmware nodes to two. What we need is to
> drop the link from struct fwnode_handle, move it to upper layer and modify
> all fwnode ops to be used over the list of fwnode:s.
> 
> XHCI driver and DWC3 are sharing the primary fwnode, but at the same time
> they wanted to have _different_ secondary ones when role is switched. This
> can’t be done in the current design. And here is the symptom what you got.

Andy, thanks for the pointers so far. I was able to trace
set_primary_fwnode() and set_secondary_fwnode().

Anyway, what's the "upper layer"? Is that "struct device" or "struct
swnode"? I suppose you meant:

- 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?