linux-kernel - Re: [PATCH] ACPI / LPSS: Do not instiate a platform

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Message-ID: <CAJZ5v0iFwWB+3oooV+vZM99SQnUpA-kuYYaNQsre9e_T_UeBxA@mail.gmail.com>
Date:   Mon, 15 Jan 2018 00:36:01 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Linux PWM List <linux-pwm@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / LPSS: Do not instiate a platform_dev for devs
 without a mmio resource

On Sun, Jan 14, 2018 at 9:01 PM, Hans de Goede <hdegoede@...hat.com> wrote:
> acpi_lpss_create_device() skips handling LPSS devices which do not have
> a mmio resources in their resource list (typically these devices are
> disabled by the firmware). But since the LPSS code does not bind to the
> device, acpi_bus_attach() ends up still creating a platform device for
> it and the regular platform_driver for the ACPI HID still tries to bind
> to it.
>
> This happens e.g. on some boards which do not use the pwm-controller
> and have an empty or invalid resource-table for it. Currently this causes
> these error messages to get logged:
> [    3.281966] pwm-lpss 80862288:00: invalid resource
> [    3.287098] pwm-lpss: probe of 80862288:00 failed with error -22
>
> This commit stops the undesirable creation of a platform_device for
> disabled LPSS devices by setting pnp.type.platform_id to 0. Note that
> acpi_scan_attach_handler() also sets pnp.type.platform_id to 0 when there
> is a matching handler for the device and that handler has no attach
> callback, so we simply behave as a handler without an attach function
> in this case.
>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

Does this fix new behavior or is it an old issue?

> ---
>  drivers/acpi/acpi_lpss.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
> index 9cfe6b71078b..166a8e582d96 100644
> --- a/drivers/acpi/acpi_lpss.c
> +++ b/drivers/acpi/acpi_lpss.c
> @@ -610,6 +610,8 @@ static int acpi_lpss_create_device(struct acpi_device *adev,
>         acpi_dev_free_resource_list(&resource_list);
>
>         if (!pdata->mmio_base) {
> +               /* Avoid acpi_bus_attach() instantiating a pdev for this dev. */
> +               adev->pnp.type.platform_id = 0;
>                 /* Skip the device, but continue the namespace scan. */
>                 ret = 0;
>                 goto err_out;
> --
> 2.14.3
>
> --
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