[PATCH v7 12/14] media: ipu3-cio2: Defer probing until the PMIC is fully setup

[Hans de Goede <hdegoede@redhat.com>]

On devices where things are not fully describe in devicetree (1)
and where the code thus falls back to calling cio2_bridge_init(),
the i2c-clients for any VCMs also need to be instantiated manually.

The VCM can be probed by its driver as soon as the code instantiates
the i2c-client and this probing must not happen before the PMIC is
fully setup.

Make cio2_bridge_init() return -EPROBE_DEFER when the PMIC is not
fully-setup, deferring the probe of the ipu3-cio2 driver.

This is a preparation patch for adding VCM enumeration support to
the ipu3-cio2-bridge code.

1) Through embedding of devicetree info in the ACPI tables

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v7:
- Make the new cio2_bridge_sensors_are_ready() function static

Changes in v6:
- New patch in v6 of this patch series
---
 drivers/media/pci/intel/ipu3/cio2-bridge.c | 37 ++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
index 1cbbcbf4e157..c805916d0909 100644
--- a/drivers/media/pci/intel/ipu3/cio2-bridge.c
+++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
@@ -308,6 +308,40 @@ static int cio2_bridge_connect_sensors(struct cio2_bridge *bridge,
 	return ret;
 }
 
+/*
+ * The VCM cannot be probed until the PMIC is completely setup. We cannot rely
+ * on -EPROBE_DEFER for this, since the consumer<->supplier relations between
+ * the VCM and regulators/clks are not described in ACPI, instead they are
+ * passed as board-data to the PMIC drivers. Since -PROBE_DEFER does not work
+ * for the clks/regulators the VCM i2c-clients must not be instantiated until
+ * the PMIC is fully setup.
+ *
+ * The sensor/VCM ACPI device has an ACPI _DEP on the PMIC, check this using the
+ * acpi_dev_ready_for_enumeration() helper, like the i2c-core-acpi code does
+ * for the sensors.
+ */
+static int cio2_bridge_sensors_are_ready(void)
+{
+	struct acpi_device *adev;
+	bool ready = true;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {
+		const struct cio2_sensor_config *cfg =
+			&cio2_supported_sensors[i];
+
+		for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
+			if (!adev->status.enabled)
+				continue;
+
+			if (!acpi_dev_ready_for_enumeration(adev))
+				ready = false;
+		}
+	}
+
+	return ready;
+}
+
 int cio2_bridge_init(struct pci_dev *cio2)
 {
 	struct device *dev = &cio2->dev;
@@ -316,6 +350,9 @@ int cio2_bridge_init(struct pci_dev *cio2)
 	unsigned int i;
 	int ret;
 
+	if (!cio2_bridge_sensors_are_ready())
+		return -EPROBE_DEFER;
+
 	bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
 	if (!bridge)
 		return -ENOMEM;
-- 
2.33.1