Re: Dell Inc. XPS 13 9343/0TM99H fails to boot v4.16-rc5

[Darren Hart]

On Tue, Mar 13, 2018 at 07:07:26AM +0000, Mario.Limonciello@xxxxxxxx wrote:
> > -----Original Message-----
> > From: Dominik Brodowski [mailto:linux@xxxxxxxxxxxxxxxxxxxx]
> > Sent: Tuesday, March 13, 2018 2:44 PM
> > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx>; Darren Hart
> > <dvhart@xxxxxxxxxxxxx>
> > Cc: platform-driver-x86@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > Subject: Re: Dell Inc. XPS 13 9343/0TM99H fails to boot v4.16-rc5
> > 
> > On Tue, Mar 13, 2018 at 06:12:04AM +0000, Mario.Limonciello@xxxxxxxx wrote:
> > > As long as they're ready before dell-laptop's initialization which uses
> > > late_initcall that should be fine.
> > >
> > > Am I correct to presume you're going to propose a patch you can test and
> > > confirm your hypothesis rather than Darren reverting my patch to bring
> > > them together?
> > 
> > Thanks for the input; a draft patch (which works fine on my system) is
> > attached below.
> > 
> > On Mon, Mar 12, 2018 at 11:32:13PM -0700, Darren Hart wrote:
> > > There is one other caveat, which you'll find documented in
> > > dell-laptop.c, namely that dell-laptop needs to init after dell-rbtn
> > > (I'm starting to appreciate the monolithic thinkpad-acpi driver).
> > >
> > > We need things to init in this order (items on the same line have no
> > > dependency):
> > >
> > > 1. DCDBAS, ACPI_WMI
> > > 2. DELL_SMBIOS, DELL_RBTN
> > > 3. DELL_LAPTOP, DELL_WMI
> > >
> > > Currently:
> > > subsys_initcall: ACPI_WMI, DELL_SMBIOS
> > > module_init: DCDBAS, DELL_WMI
> > > late_initcall: DELL_LAPTOP
> > >
> > > From a quick naive glance, it appears as though we might be able to
> > > address this as follows:
> > >
> > > subsys_initcall: DCDBAS, ACPI_WMI
> > > module_init: DELL_SMBIOS, DELL_RBTN
> > > late_initcall: DELL_LAPTOP, DELL_WMI
> > 
> > Hmmm. I do not yet understand why you propose to
> > 
> > a) advance the DCDBAS initialization to subsys_initcall, as only DELL_LAPTOP
> >    (running as a late_initcall) requires it to be up and running, and
> 
> Actually dell-smbios itself should require this too.  The SMM backend will use
> it during initialization to determine if WSMT is enabled.  If it's not operational
> yet then we may get invalid results.
>

Exactly.

> So considering this I think Darren's proposal is good to move DCDBAS to earlier.
> 
> > 
> > b) delay DELL_WMI to late_initcall, as it can safely be initialized as long
> >    as ACPI_WMI is ready.
> 
> Maybe Darren meant dell-wmi-descriptor not dell-wmi?
> Otherwise I would agree that part isn't needed.

Like DELL_LAPTOP, DELL_WMI depends on smbios being ready, so needs to
init after DELL_SMBIOS as well.

-- 
Darren Hart
VMware Open Source Technology Center