linux-kernel - Re: [PATCH v3 02/11] i2c: acpi: Use acpi_dev_ready_for

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Message-ID: <CAJZ5v0gBALWzpdmy1H3FLqFLqf3wXyVQwFRz99PJo06x53dHcQ@mail.gmail.com>
Date:   Wed, 13 Oct 2021 19:39:41 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Mark Gross <markgross@...nel.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kate Hsuan <hpa@...hat.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v3 02/11] i2c: acpi: Use acpi_dev_ready_for_enumeration() helper

On Sun, Oct 10, 2021 at 8:57 PM Hans de Goede <hdegoede@...hat.com> wrote:
>
> The clk and regulator frameworks expect clk/regulator consumer-devices
> to have info about the consumed clks/regulators described in the device's
> fw_node.
>
> To work around cases where this info is not present in the firmware tables,
> which is often the case on x86/ACPI devices, both frameworks allow the
> provider-driver to attach info about consumers to the clks/regulators
> when registering these.
>
> This causes problems with the probe ordering wrt drivers for consumers
> of these clks/regulators. Since the lookups are only registered when the
> provider-driver binds, trying to get these clks/regulators before then
> results in a -ENOENT error for clks and a dummy regulator for regulators.
>
> To ensure the correct probe-ordering the ACPI core has code to defer the
> enumeration of consumers affected by this until the providers are ready.
>
> Call the new acpi_dev_ready_for_enumeration() helper to avoid
> enumerating / instantiating i2c-clients too early.
>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
>  drivers/i2c/i2c-core-acpi.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> index aaeeacc12121..688cc71d650d 100644
> --- a/drivers/i2c/i2c-core-acpi.c
> +++ b/drivers/i2c/i2c-core-acpi.c
> @@ -144,9 +144,12 @@ static int i2c_acpi_do_lookup(struct acpi_device *adev,
>         struct list_head resource_list;
>         int ret;
>
> -       if (acpi_bus_get_status(adev) || !adev->status.present)
> +       if (acpi_bus_get_status(adev))
>                 return -EINVAL;
>
> +       if (!acpi_dev_ready_for_enumeration(adev))
> +               return -ENODEV;
> +
>         if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
>                 return -ENODEV;

I kind of prefer combining checks that cause the same error code to be
returned, but this is fine with me too.