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Date:   Wed, 27 Oct 2021 20:52:55 +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 v4 01/11] ACPI: delay enumeration of devices with a _DEP
 pointing to an INT3472 device

On Mon, Oct 25, 2021 at 11:41 AM 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.
>
> One case where we hit this issue is camera sensors such as e.g. the OV8865
> sensor found on the Microsoft Surface Go. The sensor uses clks, regulators
> and GPIOs provided by a TPS68470 PMIC which is described in an INT3472
> ACPI device. There is special platform code handling this and setting
> platform_data with the necessary consumer info on the MFD cells
> instantiated for the PMIC under: drivers/platform/x86/intel/int3472.
>
> For this to work properly the ov8865 driver must not bind to the I2C-client
> for the OV8865 sensor until after the TPS68470 PMIC gpio, regulator and
> clk MFD cells have all been fully setup.
>
> The OV8865 on the Microsoft Surface Go is just one example, all X86
> devices using the Intel IPU3 camera block found on recent Intel SoCs
> have similar issues where there is an INT3472 HID ACPI-device, which
> describes the clks and regulators, and the driver for this INT3472 device
> must be fully initialized before the sensor driver (any sensor driver)
> binds for things to work properly.
>
> On these devices the ACPI nodes describing the sensors all have a _DEP
> dependency on the matching INT3472 ACPI device (there is one per sensor).
>
> This allows solving the probe-ordering problem by delaying the enumeration
> (instantiation of the I2C-client in the ov8865 example) of ACPI-devices
> which have a _DEP dependency on an INT3472 device.
>
> The new acpi_dev_ready_for_enumeration() helper used for this is also
> exported because for devices, which have the enumeration_by_parent flag
> set, the parent-driver will do its own scan of child ACPI devices and
> it will try to enumerate those during its probe(). Code doing this such
> as e.g. the i2c-core-acpi.c code must call this new helper to ensure
> that it too delays the enumeration until all the _DEP dependencies are
> met on devices which have the new honor_deps flag set.
>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
> Changes in v4:
> - Move the acpi_dev_ready_for_enumeration() check to acpi_bus_attach()
>   (replacing the acpi_device_is_present() check there)
> ---
>  drivers/acpi/scan.c     | 37 +++++++++++++++++++++++++++++++++----
>  include/acpi/acpi_bus.h |  5 ++++-
>  2 files changed, 37 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 5b54c80b9d32..8a4cf12f8453 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -796,6 +796,12 @@ static const char * const acpi_ignore_dep_ids[] = {
>         NULL
>  };
>
> +/* List of HIDs for which we honor deps of matching ACPI devs, when checking _DEP lists. */
> +static const char * const acpi_honor_dep_ids[] = {
> +       "INT3472", /* Camera sensor PMIC / clk and regulator info */
> +       NULL
> +};
> +
>  static struct acpi_device *acpi_bus_get_parent(acpi_handle handle)
>  {
>         struct acpi_device *device = NULL;
> @@ -1757,8 +1763,12 @@ static void acpi_scan_dep_init(struct acpi_device *adev)
>         struct acpi_dep_data *dep;
>
>         list_for_each_entry(dep, &acpi_dep_list, node) {
> -               if (dep->consumer == adev->handle)
> +               if (dep->consumer == adev->handle) {
> +                       if (dep->honor_dep)
> +                               adev->flags.honor_deps = 1;
> +
>                         adev->dep_unmet++;
> +               }
>         }
>  }
>
> @@ -1962,7 +1972,7 @@ static u32 acpi_scan_check_dep(acpi_handle handle, bool check_dep)
>         for (count = 0, i = 0; i < dep_devices.count; i++) {
>                 struct acpi_device_info *info;
>                 struct acpi_dep_data *dep;
> -               bool skip;
> +               bool skip, honor_dep;
>
>                 status = acpi_get_object_info(dep_devices.handles[i], &info);
>                 if (ACPI_FAILURE(status)) {
> @@ -1971,6 +1981,7 @@ static u32 acpi_scan_check_dep(acpi_handle handle, bool check_dep)
>                 }
>
>                 skip = acpi_info_matches_ids(info, acpi_ignore_dep_ids);
> +               honor_dep = acpi_info_matches_ids(info, acpi_honor_dep_ids);
>                 kfree(info);
>
>                 if (skip)
> @@ -1984,6 +1995,7 @@ static u32 acpi_scan_check_dep(acpi_handle handle, bool check_dep)
>
>                 dep->supplier = dep_devices.handles[i];
>                 dep->consumer = handle;
> +               dep->honor_dep = honor_dep;
>
>                 mutex_lock(&acpi_dep_list_lock);
>                 list_add_tail(&dep->node , &acpi_dep_list);
> @@ -2150,8 +2162,8 @@ static void acpi_bus_attach(struct acpi_device *device, bool first_pass)
>                 register_dock_dependent_device(device, ejd);
>
>         acpi_bus_get_status(device);
> -       /* Skip devices that are not present. */
> -       if (!acpi_device_is_present(device)) {
> +       /* Skip devices that are not ready for enumeration (e.g. not present) */
> +       if (!acpi_dev_ready_for_enumeration(device)) {
>                 device->flags.initialized = false;
>                 acpi_device_clear_enumerated(device);
>                 device->flags.power_manageable = 0;
> @@ -2313,6 +2325,23 @@ void acpi_dev_clear_dependencies(struct acpi_device *supplier)
>  }
>  EXPORT_SYMBOL_GPL(acpi_dev_clear_dependencies);
>
> +/**
> + * acpi_dev_ready_for_enumeration - Check if the ACPI device is ready for enumeration
> + * @device: Pointer to the &struct acpi_device to check
> + *
> + * Check if the device is present and has no unmet dependencies.
> + *
> + * Return true if the device is ready for enumeratino. Otherwise, return false.
> + */
> +bool acpi_dev_ready_for_enumeration(const struct acpi_device *device)
> +{
> +       if (device->flags.honor_deps && device->dep_unmet)
> +               return false;
> +
> +       return acpi_device_is_present(device);
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_ready_for_enumeration);
> +
>  /**
>   * acpi_dev_get_first_consumer_dev - Return ACPI device dependent on @supplier
>   * @supplier: Pointer to the dependee device
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 13d93371790e..2da53b7b4965 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -202,7 +202,8 @@ struct acpi_device_flags {
>         u32 coherent_dma:1;
>         u32 cca_seen:1;
>         u32 enumeration_by_parent:1;
> -       u32 reserved:19;
> +       u32 honor_deps:1;
> +       u32 reserved:18;
>  };
>
>  /* File System */
> @@ -284,6 +285,7 @@ struct acpi_dep_data {
>         struct list_head node;
>         acpi_handle supplier;
>         acpi_handle consumer;
> +       bool honor_dep;
>  };
>
>  /* Performance Management */
> @@ -693,6 +695,7 @@ static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
>  bool acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, const char *uid2);
>
>  void acpi_dev_clear_dependencies(struct acpi_device *supplier);
> +bool acpi_dev_ready_for_enumeration(const struct acpi_device *device);
>  struct acpi_device *acpi_dev_get_first_consumer_dev(struct acpi_device *supplier);
>  struct acpi_device *
>  acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const char *uid, s64 hrv);
> --
> 2.31.1
>

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