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Message-Id: <1426363131-14530-1-git-send-email-jason.ekstrand@intel.com>
Date: Sat, 14 Mar 2015 12:58:51 -0700
From: Jason Ekstrand <jason@...kstrand.net>
To: linux-kernel@...r.kernel.org
Cc: Jason Ekstrand <jason@...kstrand.net>
Subject: RE: [PATCH] ACPI: Adjust the return value of _REV on x86
From: Jason Ekstrand <jason@...kstrand.net>
On Wed, 11 Mar 2015 22:50:47, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> The ACPI spec describes _REV as:
>
> "This predefined object evaluates to the revision of the ACPI Specification
> that the specified \_OS implements"
>
> We've been assuming that this should increment as ACPICA gains support for
> new versions of the spec. Unfortunately, Windows always reports "2" for this
> value and vendors are now using this as a means to tell whether a system is
> running Windows or Linux. From an HP Envy 15:
>
> If (LOr (LEqual (_REV, 0x03), LEqual (_REV, 0x05)))
>
> From a Dell XPS 13:
>
> If ((_REV == 0x05))
I can confirm that on my 2015 Dell XPS 13, this patch fixes both the audio
and suspend/resume. I'm running a build of Linus' master branch as of some
time this morning. Without this patch applied I have no audio and suspend
fails leaving the system unresponsive but the keyboard light still on and
the fan running indefinitely. With this patch, I get audio and
suspend/resume works normally.
--Jason Ekstrand
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