ACPI / property: Drop size_prop from acpi_dev_get_property_reference()

The size_prop argument of the recently added function
acpi_dev_get_property_reference() is not used by the only current
caller of that function and is very unlikely to be used at any time
going forward.

Namely, for a property whose value is a list of items each containing
a references to a device object possibly accompanied by some integers,
the number of items in the list can always be computed as the number
of elements of type ACPI_TYPE_LOCAL_REFERENCE in the property package.
Thus it should never be necessary to provide an additional "cells"
property with a value equal to the number of items in that list.  It
also should never be necessary to provide a "cells" property specifying
how many integers are supposed to be following each reference.

For this reason, drop the size_prop argument from
acpi_dev_get_property_reference() and update its caller accordingly.

Link: http://marc.info/?l=linux-kernel&m=141511255610556&w=2
Suggested-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 19 insertions, 49 deletions

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 27add91bc270..0d083736e25b 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -273,25 +273,21 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_property_array);
  * acpi_dev_get_property_reference - returns handle to the referenced object
  * @adev: ACPI device to get property
  * @name: Name of the property
- * @size_prop: Name of the "size" property in referenced object
  * @index: Index of the reference to return
  * @args: Location to store the returned reference with optional arguments
  *
  * Find property with @name, verifify that it is a package containing at least
  * one object reference and if so, store the ACPI device object pointer to the
- * target object in @args->adev.
+ * target object in @args->adev.  If the reference includes arguments, store
+ * them in the @args->args[] array.
  *
- * If the reference includes arguments (@size_prop is not %NULL) follow the
- * reference and check whether or not there is an integer property @size_prop
- * under the target object and if so, whether or not its value matches the
- * number of arguments that follow the reference.  If there's more than one
- * reference in the property value package, @index is used to select the one to
- * return.
+ * If there's more than one reference in the property value package, @index is
+ * used to select the one to return.
  *
  * Return: %0 on success, negative error code on failure.
  */
-int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
-                                    const char *size_prop, size_t index,
+int acpi_dev_get_property_reference(struct acpi_device *adev,
+                                    const char *name, size_t index,
                                     struct acpi_reference_args *args)
 {
         const union acpi_object *element, *end;
@@ -308,7 +304,7 @@ int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
          * return that reference then.
          */
         if (obj->type == ACPI_TYPE_LOCAL_REFERENCE) {
-                if (size_prop || index)
+                if (index)
                         return -EINVAL;
 
                 ret = acpi_bus_get_device(obj->reference.handle, &device);
@@ -348,42 +344,16 @@ int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
                 element++;
                 nargs = 0;
 
-                if (size_prop) {
-                        const union acpi_object *prop;
-
-                        /*
-                         * Find out how many arguments the refenced object
-                         * expects by reading its size_prop property.
-                         */
-                        ret = acpi_dev_get_property(device, size_prop,
-                                                    ACPI_TYPE_INTEGER, &prop);
-                        if (ret)
-                                return ret;
-
-                        nargs = prop->integer.value;
-                        if (nargs > MAX_ACPI_REFERENCE_ARGS
-                            || element + nargs > end)
-                                return -EPROTO;
+                /* assume following integer elements are all args */
+                for (i = 0; element + i < end; i++) {
+                        int type = element[i].type;
 
-                        /*
-                         * Skip to the start of the arguments and verify
-                         * that they all are in fact integers.
-                         */
-                        for (i = 0; i < nargs; i++)
-                                if (element[i].type != ACPI_TYPE_INTEGER)
-                                        return -EPROTO;
-                } else {
-                        /* assume following integer elements are all args */
-                        for (i = 0; element + i < end; i++) {
-                                int type = element[i].type;
-
-                                if (type == ACPI_TYPE_INTEGER)
-                                        nargs++;
-                                else if (type == ACPI_TYPE_LOCAL_REFERENCE)
-                                        break;
-                                else
-                                        return -EPROTO;
-                        }
+                        if (type == ACPI_TYPE_INTEGER)
+                                nargs++;
+                        else if (type == ACPI_TYPE_LOCAL_REFERENCE)
+                                break;
+                        else
+                                return -EPROTO;
                 }
 
                 if (idx++ == index) {
diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 5a4d061e787e..ba98bb59a58f 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -405,7 +405,7 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
                 dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname);
 
                 memset(&args, 0, sizeof(args));
-                ret = acpi_dev_get_property_reference(adev, propname, NULL,
+                ret = acpi_dev_get_property_reference(adev, propname,
                                                       index, &args);
                 if (ret) {
                         bool found = acpi_get_driver_gpio_data(adev, propname,
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 0902426c4521..10f2ed95645c 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -718,8 +718,8 @@ int acpi_dev_get_property(struct acpi_device *adev, const char *name,
 int acpi_dev_get_property_array(struct acpi_device *adev, const char *name,
                                 acpi_object_type type,
                                 const union acpi_object **obj);
-int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
-                                    const char *cells_name, size_t index,
+int acpi_dev_get_property_reference(struct acpi_device *adev,
+                                    const char *name, size_t index,
                                     struct acpi_reference_args *args);
 
 int acpi_dev_prop_get(struct acpi_device *adev, const char *propname,