[lkml]   [2017]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRE: Fwd: [PATCH] Add driver to force WMI Thunderbolt controller power status
> -----Original Message-----
> From: Bernat, Yehezkel []
> Sent: Wednesday, September 6, 2017 2:41 PM
> To: Limonciello, Mario <>
> Cc:;; platform-
> Subject: Re: Fwd: [PATCH] Add driver to force WMI Thunderbolt controller power
> status
> > Current implementations of Intel Thunderbolt controllers will go
> > into a low power mode when not in use.
> >
> > Many machines containing these controllers also have a GPIO wired up
> > that can force the controller awake.  This is offered via a ACPI-WMI
> > interface intended to be manipulated by a userspace utility.
> > This mechanism is provided by Intel to OEMs to include in BIOS.
> > It uses an industry wide GUID that is populated in a separate _WDG
> > entry with no binary MOF.
> >
> > This interface allow software such as fwupd to wake up thunderbolt
> > controllers to query the firmware version or flash new firmware.
> As this is a Thunderbolt specific function, maybe it's better to be
> exposed from the Thunderbolt driver?

I thought about this too, but the thunderbolt driver won't load if the
controller doesn't exist in the first place, whereas this is a platform
BIOS feature. I'll be interested to hear if Mika has a different perspective
on if this should live in the TBT driver and the proper way to do it.

> > +
> > +static DEVICE_ATTR_WO(force_power);
> > +
> I'm not sure what is the convention for permissions for this type of
> attributes but I feel like this worth being root-only writable, as it
> can be used to power-off the controller in the middle of a FW update,
> for example.

Yeah I think you're right. I'll adjust it in a follow up patch if this is the
correct way to go afterall.

 \ /
  Last update: 2017-09-06 21:51    [W:0.105 / U:14.880 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site