linux-kernel - [PATCH v1 1/3] ACPI: power: Use u8 as the power resource state data type

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Date:   Mon, 24 May 2021 17:24:16 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        David Box <david.e.box@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Dave Olsthoorn <dave@...aar.me>, Shujun Wang <wsj20369@....com>
Subject: [PATCH v1 1/3] ACPI: power: Use u8 as the power resource state data type

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Use u8 as the data type for representing the state of an ACPI
power resource.

It is s not necessary to use int for that and because subsequent
changes are going to use ACPI_POWER_RESOURCE_STATE_UNKNOWN, it is
better to adjust the data type so that the "unknown" state is
represented by the "all ones" value.

While at it, clean up acpi_power_get_state() somewhat.

No intentional functional impact.

Tested-by: Dave Olsthoorn <dave@...aar.me>
Tested-by: Shujun Wang <wsj20369@....com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/power.c |   27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/acpi/power.c
===================================================================
--- linux-pm.orig/drivers/acpi/power.c
+++ linux-pm/drivers/acpi/power.c
@@ -182,10 +182,11 @@ int acpi_extract_power_resources(union a
 	return err;
 }
 
-static int acpi_power_get_state(acpi_handle handle, int *state)
+static int acpi_power_get_state(acpi_handle handle, u8 *state)
 {
 	acpi_status status = AE_OK;
 	unsigned long long sta = 0;
+	u8 cur_state;
 
 	if (!handle || !state)
 		return -EINVAL;
@@ -194,25 +195,24 @@ static int acpi_power_get_state(acpi_han
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
 
-	*state = (sta & 0x01)?ACPI_POWER_RESOURCE_STATE_ON:
-			      ACPI_POWER_RESOURCE_STATE_OFF;
+	cur_state = sta & ACPI_POWER_RESOURCE_STATE_ON;
 
 	acpi_handle_debug(handle, "Power resource is %s\n",
-			  *state ? "on" : "off");
+			  cur_state ? "on" : "off");
 
+	*state = cur_state;
 	return 0;
 }
 
-static int acpi_power_get_list_state(struct list_head *list, int *state)
+static int acpi_power_get_list_state(struct list_head *list, u8 *state)
 {
 	struct acpi_power_resource_entry *entry;
-	int cur_state;
+	u8 cur_state = ACPI_POWER_RESOURCE_STATE_OFF;
 
 	if (!list || !state)
 		return -EINVAL;
 
 	/* The state of the list is 'on' IFF all resources are 'on'. */
-	cur_state = 0;
 	list_for_each_entry(entry, list, node) {
 		struct acpi_power_resource *resource = entry->resource;
 		acpi_handle handle = resource->device.handle;
@@ -592,7 +592,7 @@ int acpi_power_wakeup_list_init(struct l
 		struct acpi_power_resource *resource = entry->resource;
 		acpi_handle handle = resource->device.handle;
 		int result;
-		int state;
+		u8 state;
 
 		mutex_lock(&resource->resource_lock);
 
@@ -789,8 +789,8 @@ int acpi_disable_wakeup_device_power(str
 
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 {
+	u8 list_state = ACPI_POWER_RESOURCE_STATE_OFF;
 	int result = 0;
-	int list_state = 0;
 	int i = 0;
 
 	if (!device || !state)
@@ -919,7 +919,8 @@ struct acpi_device *acpi_add_power_resou
 	union acpi_object acpi_object;
 	struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
 	acpi_status status;
-	int state, result = -ENODEV;
+	int result;
+	u8 state;
 
 	acpi_bus_get_device(handle, &device);
 	if (device)
@@ -979,7 +980,8 @@ void acpi_resume_power_resources(void)
 	mutex_lock(&power_resource_list_lock);
 
 	list_for_each_entry(resource, &acpi_power_resource_list, list_node) {
-		int result, state;
+		int result;
+		u8 state;
 
 		mutex_lock(&resource->resource_lock);
 
@@ -1012,7 +1014,8 @@ static void acpi_power_turn_off_if_unuse
 		if (resource->users > 0)
 			return;
 	} else {
-		int result, state;
+		int result;
+		u8 state;
 
 		result = acpi_power_get_state(resource->device.handle, &state);
 		if (result || state == ACPI_POWER_RESOURCE_STATE_OFF)