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Message-ID: <5423E40B.8010302@intel.com>
Date: Thu, 25 Sep 2014 17:44:43 +0800
From: Lan Tianyu <tianyu.lan@...el.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
CC: lenb@...nel.org, mika.westerberg@...ux.intel.com,
wsa@...-dreams.de, robert.moore@...el.com, lv.zheng@...el.com,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-i2c@...r.kernel.org
Subject: Re: [RFC PATCH] ACPI: Add _DEP(Operation Region Dependencies) support
to fix battery issue on the Asus T100TA
On 2014年09月25日 06:27, Rafael J. Wysocki wrote:
> On Tuesday, September 23, 2014 03:06:43 PM Lan Tianyu wrote:
>> 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_bus_dep_device_list and adding dep_present flags in the struct
>> acpi_device. During ACPI namespace scan, all devices with _DEP support will be put
>> into the new list and those devices' dep_present flag will be set. Driver's probe()
>> should return EPROBE_DEFER when find dep_present is set. When I2C operation
>> region handler is installed, check all devices on the new list. Remove the one from
>> list if _DEP condition is met and clear its dep_present flag and do acpi_bus_attch()
>> for the device in order to resolve battery _STA issue on the Asus T100TA.
>>
>> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
>
> This is going in the right direction in my view, but isn't there just yet.
>
> Details below.
Thanks for review.
>
>> ---
>> drivers/acpi/battery.c | 4 +++
>> drivers/acpi/scan.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
>> drivers/i2c/i2c-acpi.c | 1 +
>> include/acpi/acpi_bus.h | 2 ++
>> include/linux/acpi.h | 3 ++
>> 5 files changed, 94 insertions(+)
>>
>> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
>> index 1c162e7..c0a68ce 100644
>> --- a/drivers/acpi/battery.c
>> +++ b/drivers/acpi/battery.c
>> @@ -1194,6 +1194,10 @@ static int acpi_battery_add(struct acpi_device *device)
>>
>> if (!device)
>> return -EINVAL;
>> +
>> + if (device->dep_present)
>
> device->flags.dep_present would be better. Or even call the flag dep_unmet.
Ok. Will update.
>
>> + 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 3bf7764..a26dbb3 100644
>> --- a/drivers/acpi/scan.c
>> +++ b/drivers/acpi/scan.c
>> @@ -36,6 +36,7 @@ bool acpi_force_hot_remove;
>>
>> static const char *dummy_hid = "device";
>>
>> +static LIST_HEAD(acpi_bus_dep_device_list);
>> static LIST_HEAD(acpi_bus_id_list);
>> static DEFINE_MUTEX(acpi_scan_lock);
>> static LIST_HEAD(acpi_scan_handlers_list);
>> @@ -43,6 +44,11 @@ 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;
>> + struct acpi_device *adev;
>> +};
>> +
>> struct acpi_device_bus_id{
>> char bus_id[15];
>> unsigned int instance_no;
>> @@ -2048,6 +2054,32 @@ 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;
>> + acpi_status status;
>> +
>> + if (!acpi_has_method(adev->handle, "_DEP"))
>> + return;
>> +
>> + status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
>> + &adev->dep_devices);
>> + if (ACPI_FAILURE(status)) {
>> + dev_err(&adev->dev, "Fail to evaluate _DEP.\n");
>
> "Failed"
>
>> + return;
>> + }
>> +
>> + dep = kzalloc(sizeof(struct acpi_dep_data), GFP_KERNEL);
>> + if (!dep) {
>> + dev_err(&adev->dev, "Memory allocation error.\n");
>
> "Not enough memory for _DEP list entry\n"
>
>> + return;
>> + }
>> +
>> + dep->adev = adev;
>> + adev->dep_present = true;
>> + list_add_tail(&dep->node , &acpi_bus_dep_device_list);
>> +}
>> +
>> static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
>> void *not_used, void **return_value)
>> {
>> @@ -2074,6 +2106,7 @@ 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)
>> @@ -2191,6 +2224,57 @@ static void acpi_bus_attach(struct acpi_device *device)
>> acpi_bus_attach(child);
>> }
>>
>> +static int acpi_device_dep_check(struct acpi_device *adev)
>> +{
>> + struct acpi_device *dep_adev;
>> + struct acpi_device_physical_node *pn;
>> + int i;
>> +
>> + for (i = 0; i < adev->dep_devices.count; i++) {
>> + dep_adev = acpi_bus_get_acpi_device(
>> + adev->dep_devices.handles[i]);
>> +
>> + if (!dep_adev)
>> + return -ENODEV;
>> +
>> + /* Check acpi device driver probing */
>> + if (dep_adev->dev.driver)
>> + continue;
>
> This check isn't sufficient, because _DEP is supposed to be about operation
> regions being present, not about drivers being present. Same for the driver
> check below.
>
> I wouldn't bother to check drivers in this stub implementation. ->
Sounds like we need to check whether the dependent device node has been
attached with operation region handler and this needs ACPICA to expose
such function, right?
>
>> +
>> + if (!dep_adev->physical_node_count)
>> + return -ENODEV;
>> +
>> + /* Check physcial device node driver probing */
>> + mutex_lock(&dep_adev->physical_node_lock);
>> + list_for_each_entry(pn, &dep_adev->physical_node_list, node) {
>> + if (pn->dev->driver) {
>> + mutex_unlock(&dep_adev->physical_node_lock);
>> + continue;
>> + }
>> + }
>> + mutex_unlock(&dep_adev->physical_node_lock);
>> + return -EFAULT;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int acpi_walk_dep_device_list(void)
>
> -> I'd pass the operation region device to that (and I'd call the function
> differently, but that's a detail). Then, I'd just clear flags.dep_unmet
> for all devices having that operation region device in their dep_devices
> (and drop their entries from the list). It wouldn't cover the case when
> one device depends on two operation regions at the same time (in a meaningful
> way), but should be sufficient to address the battery problem at hand.
>
This requires the dependent devices have a list to record devices which
depends on them, right? Create such lists during ACPI namespace scan.
>> +{
>> + struct acpi_dep_data *dep, *tmp;
>> +
>> + list_for_each_entry_safe(dep, tmp, &acpi_bus_dep_device_list, node) {
>> + if (!acpi_device_dep_check(dep->adev)) {
>> + dep->adev->dep_present = false;
>> + acpi_bus_attach(dep->adev);
>> + list_del(&dep->node);
>> + kfree(dep);
>> + }
>> + }
>> + return 0;
>> +}
>> +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-acpi.c b/drivers/i2c/i2c-acpi.c
>> index 0dbc18c..fdc8dc8 100644
>> --- a/drivers/i2c/i2c-acpi.c
>> +++ b/drivers/i2c/i2c-acpi.c
>> @@ -339,6 +339,7 @@ int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
>> return -ENOMEM;
>> }
>>
>> + acpi_walk_dep_device_list();
>> return 0;
>> }
>>
>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
>> index c1c9de1..c1e7055 100644
>> --- a/include/acpi/acpi_bus.h
>> +++ b/include/acpi/acpi_bus.h
>> @@ -357,7 +357,9 @@ struct acpi_device {
>> struct acpi_hotplug_context *hp;
>> struct acpi_driver *driver;
>> void *driver_data;
>> + bool dep_present;
>> struct device dev;
>> + struct acpi_handle_list dep_devices;
>> unsigned int physical_node_count;
>> struct list_head physical_node_list;
>> struct mutex physical_node_lock;
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 807cbc4..c9a504b 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -431,6 +431,7 @@ static inline bool acpi_driver_match_device(struct device *dev,
>>
>> int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
>> int acpi_device_modalias(struct device *, char *, int);
>> +int acpi_walk_dep_device_list(void);
>>
>> #define ACPI_PTR(_ptr) (_ptr)
>>
>> @@ -449,6 +450,8 @@ static inline const char *acpi_dev_name(struct acpi_device *adev)
>>
>> static inline void acpi_early_init(void) { }
>>
>> +static inline int acpi_walk_dep_device_list(void) { }
>> +
>> static inline int early_acpi_boot_init(void)
>> {
>> return 0;
>>
>
--
Best regards
Tianyu Lan
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