linux-kernel - Re: [PATCH v1 12/18] driver core: Add fw_devlink_parse

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Date:   Mon, 16 Nov 2020 17:25:32 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        "Cc: Android Kernel" <kernel-team@...roid.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v1 12/18] driver core: Add fw_devlink_parse_fwtree()

On Thu, Nov 5, 2020 at 12:24 AM Saravana Kannan <saravanak@...gle.com> wrote:
>
> This function is a wrapper around fwnode_operations.add_links().
>
> This function parses each node in a fwnode tree and create fwnode links
> for each of those nodes. The information for creating the fwnode links
> (the supplier and consumer fwnode) is obtained by parsing the properties
> in each of the fwnodes.
>
> This function also ensures that no fwnode is parsed more than once by
> marking the fwnodes as parsed.
>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/base/core.c    | 19 +++++++++++++++++++
>  include/linux/fwnode.h |  3 +++
>  2 files changed, 22 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 4a0907574646..ee28d8c7ee85 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1543,6 +1543,25 @@ static bool fw_devlink_is_permissive(void)
>         return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
>  }
>
> +static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
> +{
> +       if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
> +               return;

Why is the flag needed?

Duplicate links won't be created anyway and it doesn't cause the tree
walk to be terminated.

> +
> +       fwnode_call_int_op(fwnode, add_links, NULL);
> +       fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
> +}
> +
> +static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
> +{
> +       struct fwnode_handle *child = NULL;
> +
> +       fw_devlink_parse_fwnode(fwnode);
> +
> +       while ((child = fwnode_get_next_available_child_node(fwnode, child)))

I'd prefer

for (child = NULL; child; child =
fwnode_get_next_available_child_node(fwnode, child))

> +               fw_devlink_parse_fwtree(child);
> +}
> +
>  static void fw_devlink_link_device(struct device *dev)
>  {
>         int fw_ret;
> diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
> index ec02e1e939cc..9aaf9e4f3994 100644
> --- a/include/linux/fwnode.h
> +++ b/include/linux/fwnode.h
> @@ -15,12 +15,15 @@
>  struct fwnode_operations;
>  struct device;
>

Description here, please.

> +#define FWNODE_FLAG_LINKS_ADDED                BIT(0)
> +
>  struct fwnode_handle {
>         struct fwnode_handle *secondary;
>         const struct fwnode_operations *ops;
>         struct device *dev;
>         struct list_head suppliers;
>         struct list_head consumers;
> +       u32 flags;

That's a bit wasteful.  Maybe u8 would suffice for the time being?

>  };
>
>  struct fwnode_link {
> --
> 2.29.1.341.ge80a0c044ae-goog
>