[PATCH V3] ACPI: Add _DEP(Operation Region Dependencies) support to fix battery issue on the Asus T100TA

Lan Tianyu
2014-11-23T13:22:54Z

ACPI 5.0 introduces _DEP to designate device objects that OSPM should
assign a higher priority in start ordering due to future operation region
accesses.

On Asus T100TA, ACPI battery info are read from a I2C slave device via
I2C operation region. Before I2C operation region handler is installed,
battery _STA always returns 0. There is a _DEP method of designating
start order under battery device node.

This patch is to implement _DEP feature to fix battery issue on the Asus T100TA.
Introducing acpi_dep_list and adding dep_unmet count in the struct
acpi_device. During ACPI namespace scan, create struct acpi_dep_data for a
valid pair of master (device pointed to by _DEP)/slave(device with _DEP), record
master's and slave's ACPI handle in it and put it into acpi_dep_list. The dep_unmet
count will increase by one if there is a device under its _DEP. Driver's probe() should
return EPROBE_DEFER when find dep_unmet is larger than 0. When I2C operation
region handler is installed, remove all struct acpi_dep_data on the acpi_dep_list
whose master is pointed to I2C host controller and decrease slave's dep_unmet.
When dep_unmet decreases to 0, all _DEP conditions are met and then do acpi_bus_attach()
for the device in order to resolve battery _STA issue on the Asus T100TA.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=69011
Tested-by: Jan-Michael Brummer <jan.brummer@tabos.org>
Tested-by: Adam Williamson <adamw@happyassassin.net>
Tested-by: Michael Shigorin <shigorin@gmail.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
---
Change since V2:
Coding style change
Change since V1:
Remove redundant blank line and some coding style fixs.

drivers/acpi/battery.c | 4 +++
drivers/acpi/scan.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/i2c/i2c-core.c | 1 +
include/acpi/acpi_bus.h | 1 +
include/linux/acpi.h | 1 +
5 files changed, 92 insertions(+)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 8ec8a89..d98ba43 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -1180,6 +1180,10 @@ static int acpi_battery_add(struct acpi_device *device)

if (!device)
return -EINVAL;
+
+ if (device->dep_unmet)
+ return -EPROBE_DEFER;
+
battery = kzalloc(sizeof(struct acpi_battery), GFP_KERNEL);
if (!battery)
return -ENOMEM;
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 9cb5cca..1b1cf55 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -36,6 +36,8 @@ bool acpi_force_hot_remove;

static const char *dummy_hid = "device";

+static LIST_HEAD(acpi_dep_list);
+static DEFINE_MUTEX(acpi_dep_list_lock);
static LIST_HEAD(acpi_bus_id_list);
static DEFINE_MUTEX(acpi_scan_lock);
static LIST_HEAD(acpi_scan_handlers_list);
@@ -43,6 +45,12 @@ DEFINE_MUTEX(acpi_device_lock);
LIST_HEAD(acpi_wakeup_device_list);
static DEFINE_MUTEX(acpi_hp_context_lock);

+struct acpi_dep_data {
+ struct list_head node;
+ acpi_handle master;
+ acpi_handle slave;
+};
+
struct acpi_device_bus_id{
char bus_id[15];
unsigned int instance_no;
@@ -2193,6 +2201,59 @@ static void acpi_scan_init_hotplug(struct acpi_device *adev)
}
}

+static void acpi_device_dep_initialize(struct acpi_device *adev)
+{
+ struct acpi_dep_data *dep;
+ struct acpi_handle_list dep_devices;
+ acpi_status status;
+ int i;
+
+ if (!acpi_has_method(adev->handle, "_DEP"))
+ return;
+
+ status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
+ &dep_devices);
+ if (ACPI_FAILURE(status)) {
+ dev_err(&adev->dev, "Failed to evaluate _DEP.\n");
+ return;
+ }
+
+ for (i = 0; i < dep_devices.count; i++) {
+ struct acpi_device_info *info;
+ int skip;
+
+ status = acpi_get_object_info(dep_devices.handles[i], &info);
+ if (ACPI_FAILURE(status)) {
+ dev_err(&adev->dev, "Error reading device info\n");
+ continue;
+ }
+
+ /*
+ * Skip the dependency of Windows System Power
+ * Management Controller
+ */
+ skip = info->valid & ACPI_VALID_HID &&
+ !strcmp(info->hardware_id.string, "INT3396");
+
+ kfree(info);
+
+ if (skip)
+ continue;
+
+ dep = kzalloc(sizeof(struct acpi_dep_data), GFP_KERNEL);
+ if (!dep)
+ return;
+
+ dep->master = dep_devices.handles[i];
+ dep->slave = adev->handle;
+ adev->dep_unmet++;
+
+ mutex_lock(&acpi_dep_list_lock);
+ list_add_tail(&dep->node , &acpi_dep_list);
+ mutex_unlock(&acpi_dep_list_lock);
+ }
+}
+
static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
void *not_used, void **return_value)
{
@@ -2219,6 +2280,7 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
return AE_CTRL_DEPTH;

acpi_scan_init_hotplug(device);
+ acpi_device_dep_initialize(device);

out:
if (!*return_value)
@@ -2339,6 +2401,29 @@ static void acpi_bus_attach(struct acpi_device *device)
device->handler->hotplug.notify_online(device);
}

+void acpi_walk_dep_device_list(acpi_handle handle)
+{
+ struct acpi_dep_data *dep, *tmp;
+ struct acpi_device *adev;
+
+ mutex_lock(&acpi_dep_list_lock);
+ list_for_each_entry_safe(dep, tmp, &acpi_dep_list, node) {
+ if (dep->master == handle) {
+ acpi_bus_get_device(dep->slave, &adev);
+ if (!adev)
+ continue;
+
+ adev->dep_unmet--;
+ if (!adev->dep_unmet)
+ acpi_bus_attach(adev);
+ list_del(&dep->node);
+ kfree(dep);
+ }
+ }
+ mutex_unlock(&acpi_dep_list_lock);
+}
+EXPORT_SYMBOL_GPL(acpi_walk_dep_device_list);
+
/**
* acpi_bus_scan - Add ACPI device node objects in a given namespace scope.
* @handle: Root of the namespace scope to scan.
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index f43b4e1..68aeb8e 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -403,6 +403,7 @@ static int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
return -ENOMEM;
}

+ acpi_walk_dep_device_list(handle);
return 0;
}

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 7d1ce40..d539084 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -372,6 +372,7 @@ struct acpi_device {
void *driver_data;
struct device dev;
unsigned int physical_node_count;
+ unsigned int dep_unmet;
struct list_head physical_node_list;
struct mutex physical_node_lock;
void (*remove)(struct acpi_device *);
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 10f2ed9..e09f7f4 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -428,6 +428,7 @@ extern bool acpi_driver_match_device(struct device *dev,
const struct device_driver *drv);
int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
int acpi_device_modalias(struct device *, char *, int);
+void acpi_walk_dep_device_list(acpi_handle handle);

struct platform_device *acpi_create_platform_device(struct acpi_device *);
#define ACPI_PTR(_ptr) (_ptr)
--
1.8.4.rc0.1.g8f6a3e5.dirty