Re: [RFC 1/2] i2c: Use stable dev_name for ACPI enumerated I2C slaves

Jarkko Nikula
2013-10-28T13:15:25Z

Hi Rafael

On 10/25/2013 05:08 PM, Rafael J. Wysocki wrote:
> On Friday, October 25, 2013 04:30:23 PM Jarkko Nikula wrote:
>>>
>> Hmm, not only. Referencing to dev field in struct acpi_device by
>> dev_name(&adev->dev) here will fail too.
>
> Well, something is not quite right here.
>
> One of the *reasons* for having ACPI_HANDLE() defined this way is to
> avoid using explicit CONFIG_ACPI checks, so if that doesn't work,
> then all of that becomes a bit pointless.
>
One possible thing to do is to let structure definitions to be available
for non-ACPI builds. Then compiler won't fail on structure access which
will be anyway optimized away by later compiler stages.

With a quick test below vmlinux section sizes don't change for couple
non-ACPI build tests and allow to get rid off IS_ENABLED(CONFIG_ACPI)
test in this patch. It's very minimal as it only moves the CONFIG_ACPI
test just after the struct acpi_device definition and defines
acpi_bus_get_device for non-ACPI case.

What I don't know how consistent it is as there are still couple
structure definitions under CONFIG_ACPI, doesn't touch other acpi
headers and requires to include acpi_bus.h in driver (or move acpi_bus.h
include in linux/acpi.h currently under CONFIG_ACPI).

--
Jarkko

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index d901982..7ab7870 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -66,8 +66,6 @@ bool acpi_ata_match(acpi_handle handle);
bool acpi_bay_match(acpi_handle handle);
bool acpi_dock_match(acpi_handle handle);

-#ifdef CONFIG_ACPI
-
#include <linux/proc_fs.h>

#define ACPI_BUS_FILE_ROOT "acpi"
@@ -314,6 +312,8 @@ struct acpi_device {
void (*remove)(struct acpi_device *);
};

+#if IS_ENABLED(CONFIG_ACPI)
+
static inline void *acpi_driver_data(struct acpi_device *d)
{
return d->driver_data;
@@ -531,6 +531,8 @@ static inline bool acpi_device_can_poweroff(struct
acpi_device *adev)

static inline int register_acpi_bus_type(void *bus) { return 0; }
static inline int unregister_acpi_bus_type(void *bus) { return 0; }
+static inline int acpi_bus_get_device(acpi_handle handle,
+ struct acpi_device **device) { return 0; }

#endif /* CONFIG_ACPI */