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Subject[PATCH 1/2] ACPI: EC: Simplify acpi_ec_ecdt_start() and acpi_ec_init()
Date
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Notice that the return value of acpi_ec_init() is discarded anyway,
so it can be void and it doesn't need to check the return values of
acpi_bus_register_driver() and acpi_ec_ecdt_start() called by it.
Thus the latter can be void too and it really has nothing to do
if acpi_ec_add() has already found an EC matching the boot one in the
namespace. Also, acpi_ec_ecdt_get_handle() can be folded into it.

Modify the code accordingly and while at it create a propoer kerneldoc
comment to document acpi_ec_ecdt_start() and move the remark regarding
ASUS X550ZE along with the related bug URL from acpi_ec_init() into
that comment.

Additionally, fix up a stale comment in acpi_ec_init().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/ec.c | 91 +++++++++++++++++++------------------------------
drivers/acpi/internal.h | 2 +-
2 files changed, 37 insertions(+), 56 deletions(-)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 47baeec9190d..9e7ee6ae4706 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1594,25 +1594,6 @@ static int acpi_ec_setup(struct acpi_ec *ec, struct acpi_device *device)
return ret;
}

-static bool acpi_ec_ecdt_get_handle(acpi_handle *phandle)
-{
- struct acpi_table_ecdt *ecdt_ptr;
- acpi_status status;
- acpi_handle handle;
-
- status = acpi_get_table(ACPI_SIG_ECDT, 1,
- (struct acpi_table_header **)&ecdt_ptr);
- if (ACPI_FAILURE(status))
- return false;
-
- status = acpi_get_handle(NULL, ecdt_ptr->id, &handle);
- if (ACPI_FAILURE(status))
- return false;
-
- *phandle = handle;
- return true;
-}
-
static int acpi_ec_add(struct acpi_device *device)
{
struct acpi_ec *ec;
@@ -1784,35 +1765,42 @@ void __init acpi_ec_dsdt_probe(void)
}

/*
- * If the DSDT EC is not functioning, we still need to prepare a fully
- * functioning ECDT EC first in order to handle the events.
- * https://bugzilla.kernel.org/show_bug.cgi?id=115021
+ * acpi_ec_ecdt_start - Finalize the boot ECDT EC initialization.
+ *
+ * First, look for an ACPI handle for the boot ECDT EC if acpi_ec_add() has not
+ * found a matching object in the namespace.
+ *
+ * Next, in case the DSDT EC is not functioning, it is still necessary to
+ * provide a functional ECDT EC to handle events, so add an extra device object
+ * to represent it (see https://bugzilla.kernel.org/show_bug.cgi?id=115021).
+ *
+ * This is useful on platforms with valid ECDT and invalid DSDT EC settings,
+ * like ASUS X550ZE (see https://bugzilla.kernel.org/show_bug.cgi?id=196847).
*/
-static int __init acpi_ec_ecdt_start(void)
+static void __init acpi_ec_ecdt_start(void)
{
+ struct acpi_table_ecdt *ecdt_ptr;
acpi_handle handle;
+ acpi_status status;

- if (!boot_ec)
- return -ENODEV;
- /* In case acpi_ec_ecdt_start() is called after acpi_ec_add() */
- if (!boot_ec_is_ecdt)
- return -ENODEV;
+ /* Bail out if a matching EC has been found in the namespace. */
+ if (!boot_ec || boot_ec->handle != ACPI_ROOT_OBJECT)
+ return;

- /*
- * At this point, the namespace and the GPE is initialized, so
- * start to find the namespace objects and handle the events.
- *
- * Note: ec->handle can be valid if this function is called after
- * acpi_ec_add(), hence the fast path.
- */
- if (boot_ec->handle == ACPI_ROOT_OBJECT) {
- if (!acpi_ec_ecdt_get_handle(&handle))
- return -ENODEV;
- boot_ec->handle = handle;
- }
+ /* Look up the object pointed to from the ECDT in the namespace. */
+ status = acpi_get_table(ACPI_SIG_ECDT, 1,
+ (struct acpi_table_header **)&ecdt_ptr);
+ if (ACPI_FAILURE(status))
+ return;
+
+ status = acpi_get_handle(NULL, ecdt_ptr->id, &handle);
+ if (ACPI_FAILURE(status))
+ return;

- /* Register to ACPI bus with PM ops attached */
- return acpi_bus_register_early_device(ACPI_BUS_TYPE_ECDT_EC);
+ boot_ec->handle = handle;
+
+ /* Add a special ACPI device object to represent the boot EC. */
+ acpi_bus_register_early_device(ACPI_BUS_TYPE_ECDT_EC);
}

#if 0
@@ -2156,14 +2144,13 @@ static const struct dmi_system_id acpi_ec_no_wakeup[] = {
{ },
};

-int __init acpi_ec_init(void)
+void __init acpi_ec_init(void)
{
int result;
- int ecdt_fail, dsdt_fail;

result = acpi_ec_init_workqueues();
if (result)
- return result;
+ return;

/*
* Disable EC wakeup on following systems to prevent periodic
@@ -2174,16 +2161,10 @@ int __init acpi_ec_init(void)
pr_debug("Disabling EC wakeup on suspend-to-idle\n");
}

- /* Drivers must be started after acpi_ec_query_init() */
- dsdt_fail = acpi_bus_register_driver(&acpi_ec_driver);
- /*
- * Register ECDT to ACPI bus only when PNP0C09 probe fails. This is
- * useful for platforms (confirmed on ASUS X550ZE) with valid ECDT
- * settings but invalid DSDT settings.
- * https://bugzilla.kernel.org/show_bug.cgi?id=196847
- */
- ecdt_fail = acpi_ec_ecdt_start();
- return ecdt_fail && dsdt_fail ? -ENODEV : 0;
+ /* Driver must be registered after acpi_ec_init_workqueues(). */
+ acpi_bus_register_driver(&acpi_ec_driver);
+
+ acpi_ec_ecdt_start();
}

/* EC driver currently not unloadable */
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 3616daec650b..43411a7457cd 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -190,7 +190,7 @@ extern struct acpi_ec *first_ec;
/* External interfaces use first EC only, so remember */
typedef int (*acpi_ec_query_func) (void *data);

-int acpi_ec_init(void);
+void acpi_ec_init(void);
void acpi_ec_ecdt_probe(void);
void acpi_ec_dsdt_probe(void);
void acpi_ec_block_transactions(void);
--
2.16.4



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