Re: [PATCH v2 3/9] PCI: drop `is_thunderbolt` attribute

[Lukas Wunner <lukas@wunner.de>]

On Fri, Feb 11, 2022 at 12:23:51PM +0200, Mika Westerberg wrote:
> On Thu, Feb 10, 2022 at 04:43:23PM -0600, Mario Limonciello wrote:
> > @@ -2955,7 +2955,7 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
> >  			return true;
> >  
> >  		/* Even the oldest 2010 Thunderbolt controller supports D3. */
> > -		if (bridge->is_thunderbolt)
> > +		if (dev_is_removable(&bridge->dev))
> 
> For this, I'm not entirely sure this is what we want. The purpose of
> this check is to enable port power management of Apple systems with
> Intel Thunderbolt controller and therefore checking for "removable" here
> is kind of misleading IMHO.
[...]
> and then make a quirk in quirks.c that adds the software node property
> for the Apple systems? Or something along those lines.

Honestly, that feels wrong to me.

There are non-Apple products with Thunderbolt controllers,
e.g. Supermicro X10SAT was a Xeon board with Redwood Ridge
which was introduced in 2013.  This was way before Microsoft
came up with the HotPlugSupportInD3 property.  It was also way
before the 2015 BIOS cut-off date that we use to disable
power management on older boards.

Still, we currently whitelist the Thunderbolt ports on that
board for D3 because we know it works.  What if products like
this one use their own power management scheme and we'd cause
a power regression if we needlessly disable D3 for them now?

Thanks,

Lukas