Date: Thu, 9 Oct 2014 10:38:54 +0300
From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Loic Poulain <loic.poulain@intel.com>
Cc: johannes@sipsolutions.net, linville@tuxdriver.com,
	linux-wireless@vger.kernel.org
Subject: Re: [PATCH 3/5] net: rfkill: gpio: Implement host wake up support
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On Wed, Oct 08, 2014 at 04:09:50PM +0200, Loic Poulain wrote:
> Thanks, it sounds good to use a label instead of index.
> However:
> - DSD is only compatible with BIOS ACPI 5.1
> - gpiod_get_index does not take care of con_id (label) parameter in case of
> ACPI (acpi_find_gpio).
> - gpiod_get calls gpiod_get_index with index 0.
> 
> Any patch ongoing to support con_id parameter with ACPI?

Yes. This is the latest version being review as we speak:
https://lkml.org/lkml/2014/10/6/530

It is really important you get your firmware fixed. We simply can not
rely on the order of the resources like GPIOs in the resource
templates. They may be different on every second
board/BIOS/configuration/whatever. It's even possible for a ACPI
device object to have two (or more) different resource templates
describing the same GPIOs in different order which are then selected
based on some magic condition, for example user selection in BIOS setup.

The existing hardware works with the drivers we have now, and it's not
possible to change the BIOS/system firmware on those so we just have
to live with them and rely on being able to pick the correct resources
based on index. But everything new _must_ use _DSD properties, and
ACPI 5.1 in general.

So basically your BIOS must produce the ACPI tables according to ACPI
5.1. If you are worried about support for ACPI 5.1 in kernel, don't
worry about it, it's almost ready. And in the meantime, _DSD is just
something kernel will ignore.


Cheers,

-- 
heikki