Merge tag 'acpi-5.16-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more ACPI updates from Rafael Wysocki:
 "These add support for a new ACPI device configuration object called
  _DSC, fix some issues including one recent regression, add two new
  items to quirk lists and clean up assorted pieces of code.

  Specifics:

   - Add support for new ACPI device configuration object called _DSC
     ("Deepest State for Configuration") to allow certain devices to be
     probed without changing their power states, document it and make
     two drivers use it (Sakari Ailus, Rajmohan Mani).

   - Fix device wakeup power reference counting broken recently by
     mistake (Rafael Wysocki).

   - Drop unused symbol and macros depending on it from acgcc.h (Rafael
     Wysocki).

   - Add HP ZHAN 66 Pro to the "no EC wakeup" quirk list (Binbin Zhou).

   - Add Xiaomi Mi Pad 2 to the backlight quirk list and drop an unused
     piece of data from all of the list entries (Hans de Goede).

   - Fix register read accesses handling in the Intel PMIC operation
     region driver (Hans de Goede).

   - Clean up static variables initialization in the EC driver
     (wangzhitong)"

* tag 'acpi-5.16-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Documentation: ACPI: Fix non-D0 probe _DSC object example
  ACPI: Drop ACPI_USE_BUILTIN_STDARG ifdef from acgcc.h
  ACPI: PM: Fix device wakeup power reference counting error
  ACPI: video: use platform backlight driver on Xiaomi Mi Pad 2
  ACPI: video: Drop dmi_system_id.ident settings from video_detect_dmi_table[]
  ACPI: PMIC: Fix intel_pmic_regs_handler() read accesses
  ACPI: EC: Remove initialization of static variables to false
  ACPI: EC: Use ec_no_wakeup on HP ZHAN 66 Pro
  at24: Support probing while in non-zero ACPI D state
  media: i2c: imx319: Support device probe in non-zero ACPI D state
  ACPI: Add a convenience function to tell a device is in D0 state
  Documentation: ACPI: Document _DSC object usage for enum power state
  i2c: Allow an ACPI driver to manage the device's power state during probe
  ACPI: scan: Obtain device's desired enumeration power state

Author: torvalds

Documentation/firmware-guide/acpi/index.rst

@@ -26,5 +26,6 @@ ACPI Support
    acpi-lid
    lpit
    video_extension
+   non-d0-probe
    extcon-intel-int3496
    intel-pmc-mux

Documentation/firmware-guide/acpi/non-d0-probe.rst

@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================================
+Probing devices in other D states than 0
+========================================
+
+Introduction
+============
+
+In some cases it may be preferred to leave certain devices powered off for the
+entire system bootup if powering on these devices has adverse side effects,
+beyond just powering on the said device.
+
+How it works
+============
+
+The _DSC (Device State for Configuration) object that evaluates to an integer
+may be used to tell Linux the highest allowed D state for a device during
+probe. The support for _DSC requires support from the kernel bus type if the
+bus driver normally sets the device in D0 state for probe.
+
+The downside of using _DSC is that as the device is not powered on, even if
+there's a problem with the device, the driver likely probes just fine but the
+first user will find out the device doesn't work, instead of a failure at probe
+time. This feature should thus be used sparingly.
+
+I²C
+---
+
+If an I²C driver indicates its support for this by setting the
+I2C_DRV_ACPI_WAIVE_D0_PROBE flag in struct i2c_driver.flags field and the
+_DSC object evaluates to integer higher than the D state of the device,
+the device will not be powered on (put in D0 state) for probe.
+
+D states
+--------
+
+The D states and thus also the allowed values for _DSC are listed below. Refer
+to [1] for more information on device power states.
+
+.. code-block:: text
+
+	Number	State	Description
+	0	D0	Device fully powered on
+	1	D1
+	2	D2
+	3	D3hot
+	4	D3cold	Off
+
+References
+==========
+
+[1] https://uefi.org/specifications/ACPI/6.4/02_Definition_of_Terms/Definition_of_Terms.html#device-power-state-definitions
+
+Example
+=======
+
+An ASL example describing an ACPI device using _DSC object to tell Operating
+System the device should remain powered off during probe looks like this. Some
+objects not relevant from the example point of view have been omitted.
+
+.. code-block:: text
+
+	Device (CAM0)
+	{
+		Name (_HID, "SONY319A")
+		Name (_UID, Zero)
+		Name (_CRS, ResourceTemplate ()
+		{
+			I2cSerialBus(0x0020, ControllerInitiated, 0x00061A80,
+				     AddressingMode7Bit, "\\_SB.PCI0.I2C0",
+				     0x00, ResourceConsumer)
+		})
+		Method (_DSC, 0, NotSerialized)
+		{
+			Return (0x4)
+		}
+	}

drivers/acpi/device_pm.c

@@ -1400,4 +1400,30 @@ bool acpi_storage_d3(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(acpi_storage_d3);
 
+/**
+ * acpi_dev_state_d0 - Tell if the device is in D0 power state
+ * @dev: Physical device the ACPI power state of which to check
+ *
+ * On a system without ACPI, return true. On a system with ACPI, return true if
+ * the current ACPI power state of the device is D0, or false otherwise.
+ *
+ * Note that the power state of a device is not well-defined after it has been
+ * passed to acpi_device_set_power() and before that function returns, so it is
+ * not valid to ask for the ACPI power state of the device in that time frame.
+ *
+ * This function is intended to be used in a driver's probe or remove
+ * function. See Documentation/firmware-guide/acpi/low-power-probe.rst for
+ * more information.
+ */
+bool acpi_dev_state_d0(struct device *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+
+	if (!adev)
+		return true;
+
+	return adev->power.state == ACPI_STATE_D0;
+}
+EXPORT_SYMBOL_GPL(acpi_dev_state_d0);
+
 #endif /* CONFIG_PM */

drivers/acpi/ec.c

@@ -133,7 +133,7 @@ static unsigned int ec_storm_threshold  __read_mostly = 8;
 module_param(ec_storm_threshold, uint, 0644);
 MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");
 
-static bool ec_freeze_events __read_mostly = false;
+static bool ec_freeze_events __read_mostly;
 module_param(ec_freeze_events, bool, 0644);
 MODULE_PARM_DESC(ec_freeze_events, "Disabling event handling during suspend/resume");
 
@@ -177,7 +177,7 @@ struct acpi_ec *first_ec;
 EXPORT_SYMBOL(first_ec);
 
 static struct acpi_ec *boot_ec;
-static bool boot_ec_is_ecdt = false;
+static bool boot_ec_is_ecdt;
 static struct workqueue_struct *ec_wq;
 static struct workqueue_struct *ec_query_wq;
 
@@ -2152,6 +2152,13 @@ static const struct dmi_system_id acpi_ec_no_wakeup[] = {
 			DMI_MATCH(DMI_PRODUCT_FAMILY, "ThinkPad X1 Yoga 3rd"),
 		},
 	},
+	{
+		.ident = "HP ZHAN 66 Pro",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "HP"),
+			DMI_MATCH(DMI_PRODUCT_FAMILY, "103C_5336AN HP ZHAN 66 Pro"),
+		},
+	},
 	{ },
 };
 

drivers/acpi/pmic/intel_pmic.c

@@ -211,31 +211,36 @@ static acpi_status intel_pmic_regs_handler(u32 function,
 		void *handler_context, void *region_context)
 {
 	struct intel_pmic_opregion *opregion = region_context;
-	int result = 0;
+	int result = -EINVAL;
+
+	if (function == ACPI_WRITE) {
+		switch (address) {
+		case 0:
+			return AE_OK;
+		case 1:
+			opregion->ctx.addr |= (*value64 & 0xff) << 8;
+			return AE_OK;
+		case 2:
+			opregion->ctx.addr |= *value64 & 0xff;
+			return AE_OK;
+		case 3:
+			opregion->ctx.val = *value64 & 0xff;
+			return AE_OK;
+		case 4:
+			if (*value64) {
+				result = regmap_write(opregion->regmap, opregion->ctx.addr,
+						      opregion->ctx.val);
+			} else {
+				result = regmap_read(opregion->regmap, opregion->ctx.addr,
+						     &opregion->ctx.val);
+			}
+			opregion->ctx.addr = 0;
+		}
+	}
 
-	switch (address) {
-	case 0:
-		return AE_OK;
-	case 1:
-		opregion->ctx.addr |= (*value64 & 0xff) << 8;
-		return AE_OK;
-	case 2:
-		opregion->ctx.addr |= *value64 & 0xff;
+	if (function == ACPI_READ && address == 3) {
+		*value64 = opregion->ctx.val;
 		return AE_OK;
-	case 3:
-		opregion->ctx.val = *value64 & 0xff;
-		return AE_OK;
-	case 4:
-		if (*value64) {
-			result = regmap_write(opregion->regmap, opregion->ctx.addr,
-					      opregion->ctx.val);
-		} else {
-			result = regmap_read(opregion->regmap, opregion->ctx.addr,
-					     &opregion->ctx.val);
-			if (result == 0)
-				*value64 = opregion->ctx.val;
-		}
-		memset(&opregion->ctx, 0x00, sizeof(opregion->ctx));
 	}
 
 	if (result < 0) {

drivers/acpi/power.c

@@ -757,13 +757,11 @@ int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 
 	mutex_lock(&acpi_device_lock);
 
-	if (dev->wakeup.prepare_count > 1) {
-		dev->wakeup.prepare_count--;
+	/* Do nothing if wakeup power has not been enabled for this device. */
+	if (dev->wakeup.prepare_count <= 0)
 		goto out;
-	}
 
-	/* Do nothing if wakeup power has not been enabled for this device. */
-	if (!dev->wakeup.prepare_count)
+	if (--dev->wakeup.prepare_count > 0)
 		goto out;
 
 	err = acpi_device_sleep_wake(dev, 0, 0, 0);

drivers/acpi/scan.c

@@ -1017,6 +1017,7 @@ static void acpi_bus_init_power_state(struct acpi_device *device, int state)
 
 static void acpi_bus_get_power_flags(struct acpi_device *device)
 {
+	unsigned long long dsc = ACPI_STATE_D0;
 	u32 i;
 
 	/* Presence of _PS0|_PR0 indicates 'power manageable' */
@@ -1038,6 +1039,9 @@ static void acpi_bus_get_power_flags(struct acpi_device *device)
 	if (acpi_has_method(device->handle, "_DSW"))
 		device->power.flags.dsw_present = 1;
 
+	acpi_evaluate_integer(device->handle, "_DSC", NULL, &dsc);
+	device->power.state_for_enumeration = dsc;
+
 	/*
 	 * Enumerate supported power management states
 	 */