> -----Original Message----- > From: Bernat, Yehezkel [mailto:yehezkel.bernat@xxxxxxxxx] > Sent: Wednesday, September 6, 2017 2:41 PM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: mika.westerberg@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; platform- > driver-x86@xxxxxxx; dvhart@xxxxxxxxxxxxx; hughsient@xxxxxxxxx > 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. Thanks,
