linux-kernel - Re: [PATCH] RFC: platform/x86: wmi: Fix check for method instance number

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Message-Id: <201706220933.55718@pali>
Date:   Thu, 22 Jun 2017 09:33:55 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Mario.Limonciello@...l.com
Cc:     dvhart@...radead.org, andy@...radead.org, luto@...nel.org,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RFC: platform/x86: wmi: Fix check for method instance number

On Wednesday 21 June 2017 23:52:12 Mario.Limonciello@...l.com wrote:
> > -----Original Message-----
> > From: Pali Rohár [mailto:pali.rohar@...il.com]
> > Sent: Saturday, June 17, 2017 11:35 AM
> > To: Limonciello, Mario <Mario_Limonciello@...l.com>
> > Cc: dvhart@...radead.org; andy@...radead.org; luto@...nel.org;
> > platform-driver- x86@...r.kernel.org; linux-kernel@...r.kernel.org
> > Subject: Re: [PATCH] RFC: platform/x86: wmi: Fix check for method
> > instance number
> > 
> > On Friday 16 June 2017 18:33:54 Mario.Limonciello@...l.com wrote:
> > > > -----Original Message-----
> > > > From: Limonciello, Mario
> > > > Sent: Thursday, June 15, 2017 10:16 AM
> > > > To: 'Pali Rohár' <pali.rohar@...il.com>; Darren Hart
> > > > <dvhart@...radead.org> Cc: Andy Shevchenko
> > > > <andy@...radead.org>; Andy Lutomirski <luto@...nel.org>;
> > > > platform-driver-x86@...r.kernel.org;
> > > > linux-kernel@...r.kernel.org Subject: RE: [PATCH] RFC:
> > > > platform/x86: wmi: Fix check for method instance number
> > > > 
> > > > > -----Original Message-----
> > > > > From: Pali Rohár [mailto:pali.rohar@...il.com]
> > > > > Sent: Thursday, June 15, 2017 8:59 AM
> > > > > To: Limonciello, Mario <Mario_Limonciello@...l.com>; Darren
> > > > > Hart <dvhart@...radead.org>
> > > > > Cc: Andy Shevchenko <andy@...radead.org>; Andy Lutomirski
> > > > 
> > > > <luto@...nel.org>;
> > > > 
> > > > > platform-driver-x86@...r.kernel.org;
> > > > > linux-kernel@...r.kernel.org Subject: Re: [PATCH] RFC:
> > > > > platform/x86: wmi: Fix check for method instance number
> > > > > 
> > > > > Mario, are you able to check if instance number passed to
> > > > > wmi_evaluate_method in following dell WMI drivers is correct
> > > > > and should be really 1?
> > > > > 
> > > > > I suspect that it should be zero, as instance number is
> > > > > indexed from zero.
> > > > > 
> > > > > There is no comment in those dell WMI drivers why it is 1,
> > > > > nor what 1 means.
> > > > > 
> > > > > Ideally it needs to be checked in ACPI byte code, MOF file
> > > > > and WDG dump.
> > > > 
> > > > I think you're likely correct.  I don't have a box that
> > > > supports alienware-wmi or dell-wmi-led.c handy at the current
> > > > moment to confirm this hypothesis though. I'll confirm this
> > > > later.
> > > > 
> > > > I didn't realize it was zero indexed when I wrote
> > > > alienware-wmi, and I'm guessing the author of dell-wmi-led
> > > > didn't either.
> > > > 
> > > > The reason it's probably working is the ACPI byte code isn't
> > > > actually checking the instance since most times _WDG will only
> > > > call out one instance.
> > > 
> > > I confirmed you're correct.  Switching instance over to 0 works
> > > properly on an ASM200 (supported by alienware-wmi).
> > 
> > Can you check what is the value in the instance_count in _WDG?
> 
> Instance count is 1.
> 
> Thanks,

Ok, in this case instance number should be zero in driver code. Will you 
send patch for fixing it?

-- 
Pali Rohár
pali.rohar@...il.com

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