[alsa-devel] [PATCHv3 1/3] ACPI: Provide struct acpi_device stub for !CONFIG_ACPI builds

Jarkko Nikula jarkko.nikula at linux.intel.com
Thu Nov 14 12:14:17 CET 2013

On 11/14/2013 12:03 PM, Takashi Iwai wrote:
> At Thu, 14 Nov 2013 11:00:59 +0200,
> Jarkko Nikula wrote:
>> We have a few cases where we want to access struct device dev field in
>> struct acpi_device from generic code that is build also without CONFIG_ACPI.
>> Provide here a minimal struct acpi_device stub that allows to build such a
>> code without adding new #ifdef CONFIG_ACPI churn. This should not increase
>> section sizes if code is protected by ACPI_COMPANION() runtime checks as
>> those will be optimized out by later compiler stages in case CONFIG_ACPI is
>> not set.
>> Signed-off-by: Jarkko Nikula <jarkko.nikula at linux.intel.com>
>> ---
>> Rafael, instead of this we could also have an accessor but adev->dev looked
>> better in actual code and size vmlinux didn't change for x86_64_defconfig
>> with CONFIG_ACPI is not set nor for omap2plus_defconfig.
> This looks too hackish, IMO.  Defining a different dummy struct often
> gives more headaches.  Thinking of the potential risk by misuses, it'd
> be simpler and safer to define a macro like acpi_dev_name() instead.
> BTW, is linux/device.h already included in !CONFIG_ACPI case?
It is included unconditionally in include/linux/acpi.h.

Your acpi_dev_name() proposal may be good enough for now as adev->dev 
access in generic code (now under CONFIG_ACPI) seems to be anyway around 
dev_name, using only pointer to struct acpi_device or has more things 
that prevents immediate #ifdef CONFIG_ACPI removal there.

But one problem at time. I'll cook a version with acpi_dev_name.


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