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

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Message-ID: <8c0becdd535d4a58b5dbc72eda082e12@ausx13mpc120.AMER.DELL.COM>
Date:   Thu, 15 Jun 2017 15:16:15 +0000
From:   <Mario.Limonciello@...l.com>
To:     <pali.rohar@...il.com>, <dvhart@...radead.org>
CC:     <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

> -----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.

> On Wednesday 14 June 2017 17:46:54 Pali Rohár wrote:
> > Function wmi_evaluate_method:
> ...
> >   alienware-wmi.c:
> >   instance=1 /* no comment why, guid=A70591CE-A997-11DA-B012-
> B622A1EF5492 */
> >   instance=1 /* no comment why, guid=A80593CE-A997-11DA-B012-
> B622A1EF5492 */
> >   instance=1 /* no comment why, guid=A70591CE-A997-11DA-B012-
> B622A1EF5492 */
> ...
> >   dell-wmi-led.c:
> >   instance=1 /* no comment why, guid=F6E4FE6E-909D-47cb-8BAB-
> C9F6F2F8D396 */	
> 
> --
> Pali Rohár
> pali.rohar@...il.com