linux-kernel - Re: [PATCH v1 2/2] of: platform: Mark bus devices nodes with FWNODE_FLAG_NEVER

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Date:   Thu, 2 Sep 2021 10:20:53 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Len Brown <lenb@...nel.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v1 2/2] of: platform: Mark bus devices nodes with FWNODE_FLAG_NEVER_PROBES

On Wed, Sep 1, 2021 at 7:55 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> We don't want fw_devlink creating device links for bus devices as
> they'll never probe. So mark those device node with this flag.
>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/of/platform.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 74afbb7a4f5e..42b3936d204a 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -392,6 +392,22 @@ static int of_platform_bus_create(struct device_node *bus,
>         if (!dev || !of_match_node(matches, bus))
>                 return 0;
>
> +       /*
> +        * If the bus node has only one compatible string value and it has
> +        * matched as a bus node, it's never going to get probed by a device
> +        * driver. So flag it as such so that fw_devlink knows not to create
> +        * device links with this device.
> +        *
> +        * This doesn't catch all devices that'll never probe, but this is good
> +        * enough for now.
> +        *
> +        * This doesn't really work for PPC because of how it uses
> +        * of_platform_bus_probe() to add normal devices. So ignore PPC cases.
> +        */
> +       if (!IS_ENABLED(CONFIG_PPC) &&
> +           of_property_count_strings(bus, "compatible") == 1)
> +               bus->fwnode.flags |= FWNODE_FLAG_NOT_DEVICE;

This patch is wrong. This flag should have been FWNODE_FLAG_NEVER_PROBES.

-Saravana

> +
>         for_each_child_of_node(bus, child) {
>                 pr_debug("   create child: %pOF\n", child);
>                 rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
> --
> 2.33.0.259.gc128427fd7-goog
>