linux-kernel - Re: [PATCH v1 4/5] of: property: Make sure child dependencies don't block probing of parent

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Message-ID: <CAL_JsqJQ9siUGgmGqZnF_Wk3mVau29yVZRL_3LxFKgD8=mccQQ@mail.gmail.com>
Date:   Mon, 4 Nov 2019 11:01:16 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Len Brown <lenb@...nel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v1 4/5] of: property: Make sure child dependencies don't
 block probing of parent

On Mon, Oct 28, 2019 at 5:00 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> When creating device links to proxy the sync_state() needs of child
> dependencies, create SYNC_STATE_ONLY device links so that children
> dependencies don't block probing of the parent.
>
> Also, differentiate between missing suppliers of parent device vs
> missing suppliers of child devices so that driver core doesn't block
> parent device probing when only child supplier dependencies are missing.
>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---
>  drivers/of/property.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)

Reviewed-by: Rob Herring <robh@...nel.org>

One nit below:

>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 2808832b2e86..f16f85597ccc 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1032,10 +1032,10 @@ static bool of_is_ancestor_of(struct device_node *test_ancestor,
>   * - -EINVAL if the supplier link is invalid and should not be created
>   * - -ENODEV if there is no device that corresponds to the supplier phandle
>   */
> -static int of_link_to_phandle(struct device *dev, struct device_node *sup_np)
> +static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
> +                             u32 dl_flags)
>  {
>         struct device *sup_dev;
> -       u32 dl_flags = DL_FLAG_AUTOPROBE_CONSUMER;
>         int ret = 0;
>         struct device_node *tmp_np = sup_np;
>
> @@ -1195,13 +1195,20 @@ static int of_link_property(struct device *dev, struct device_node *con_np,
>         unsigned int i = 0;
>         bool matched = false;
>         int ret = 0;
> +       u32 dl_flags;
> +
> +       if (dev->of_node == con_np)
> +               dl_flags = DL_FLAG_AUTOPROBE_CONSUMER;
> +       else
> +               dl_flags = DL_FLAG_SYNC_STATE_ONLY;
>
>         /* Do not stop at first failed link, link all available suppliers. */
>         while (!matched && s->parse_prop) {
>                 while ((phandle = s->parse_prop(con_np, prop_name, i))) {
>                         matched = true;
>                         i++;
> -                       if (of_link_to_phandle(dev, phandle) == -EAGAIN)
> +                       if (of_link_to_phandle(dev, phandle, dl_flags)
> +                                                               == -EAGAIN)

nit: I'd just keep this one line or at least move '==' up.

>                                 ret = -EAGAIN;
>                         of_node_put(phandle);
>                 }
> @@ -1219,10 +1226,10 @@ static int of_link_to_suppliers(struct device *dev,
>
>         for_each_property_of_node(con_np, p)
>                 if (of_link_property(dev, con_np, p->name))
> -                       ret = -EAGAIN;
> +                       ret = -ENODEV;
>
>         for_each_child_of_node(con_np, child)
> -               if (of_link_to_suppliers(dev, child))
> +               if (of_link_to_suppliers(dev, child) && !ret)
>                         ret = -EAGAIN;
>
>         return ret;
> --
> 2.24.0.rc0.303.g954a862665-goog
>