linux-kernel - [PATCH v3 11/11] platform/x86: int3472: Deal with probe ordering issues

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Date:   Sun, 10 Oct 2021 20:57:07 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "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>
Cc:     Hans de Goede <hdegoede@...hat.com>, Len Brown <lenb@...nel.org>,
        linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kate Hsuan <hpa@...hat.com>, linux-media@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: [PATCH v3 11/11] platform/x86: int3472: Deal with probe ordering issues

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 this info missing from the ACPI tables on devices where
the int3472 driver is used, the int3472 MFD-cell drivers 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.

All the sensor ACPI fw-nodes have a _DEP dependency on the INT3472 ACPI
fw-node, so to work around these probe ordering issues the ACPI core /
i2c-code does not instantiate the I2C-clients for any ACPI devices
which have a _DEP dependency on an INT3472 ACPI device until all
_DEP-s are met.

This relies on acpi_dev_clear_dependencies() getting called by the driver
for the _DEP-s when they are ready, add a acpi_dev_clear_dependencies()
call to the discrete.c probe code.

In the tps68470 case calling acpi_dev_clear_dependencies() is already done
by the acpi_gpiochip_add() call done by the driver for the GPIO MFD cell
(The GPIO cell is deliberately the last cell created to make sure the
clk + regulator cells are already instantiated when this happens).

However for proper probe ordering, the clk/regulator cells must not just
be instantiated the must be fully ready (the clks + regulators must be
registered with their subsystems).

Add MODULE_SOFTDEP dependencies for the clk and regulator drivers for
the instantiated MFD-cells so that these are loaded before us and so
that they bind immediately when the platform-devs are instantiated.

Signed-off-by: Hans de Goede <hdegoede@...hat.com>
---
Changes in v2:
- Only call acpi_dev_clear_dependencies() in the discrete.c case, for the
  tps68470 case this is already done by the acpi_gpiochip_add() for the
  GPIO MFD cell.
---
 drivers/platform/x86/intel/int3472/discrete.c | 1 +
 drivers/platform/x86/intel/int3472/tps68470.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/drivers/platform/x86/intel/int3472/discrete.c b/drivers/platform/x86/intel/int3472/discrete.c
index fefe12850777..e23a45b985dc 100644
--- a/drivers/platform/x86/intel/int3472/discrete.c
+++ b/drivers/platform/x86/intel/int3472/discrete.c
@@ -380,6 +380,7 @@ static int skl_int3472_discrete_probe(struct platform_device *pdev)
 		return ret;
 	}

+	acpi_dev_clear_dependencies(adev);
 	return 0;
 }

diff --git a/drivers/platform/x86/intel/int3472/tps68470.c b/drivers/platform/x86/intel/int3472/tps68470.c
index c53c7960ee09..fcc7083e8916 100644
--- a/drivers/platform/x86/intel/int3472/tps68470.c
+++ b/drivers/platform/x86/intel/int3472/tps68470.c
@@ -173,6 +173,11 @@ static int skl_int3472_tps68470_probe(struct i2c_client *client)
 		return device_type;
 	}

+	/*
+	 * No acpi_dev_clear_dependencies() here, since the acpi_gpiochip_add()
+	 * for the GPIO cell already does this.
+	 */
+
 	return ret;
 }

@@ -206,3 +211,4 @@ module_i2c_driver(int3472_tps68470);
 MODULE_DESCRIPTION("Intel SkyLake INT3472 ACPI TPS68470 Device Driver");
 MODULE_AUTHOR("Daniel Scally <djrscally@...il.com>");
 MODULE_LICENSE("GPL v2");
+MODULE_SOFTDEP("pre: clk-tps68470 tps68470-regulator");
-- 
2.31.1