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

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi Mario,

On Thu, Feb 10, 2022 at 04:43:23PM -0600, Mario Limonciello wrote:
> The `is_thunderbolt` attribute is currently a dumping ground for a
> variety of things.
> 
> Instead use the driver core removable attribute to indicate the
> detail a device is attached to a thunderbolt or USB4 chain.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  drivers/pci/pci.c                 |  2 +-
>  drivers/pci/probe.c               | 20 +++++++-------------
>  drivers/platform/x86/apple-gmux.c |  2 +-
>  include/linux/pci.h               |  5 ++---
>  4 files changed, 11 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 9ecce435fb3f..1264984d5e6d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -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.

I wonder if we could instead remove the check completely here and rely
on the below:

	if (platform_pci_bridge_d3(bridge))
		return true;

and that would then look like:

static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
{
	if (pci_use_mid_pm())
		return false;

	if (acpi_pci_bridge_d3(dev))
		return true;

	if (device_property_read_bool(&dev->dev, "HotPlugSupportInD3"))
		return true;

	return false;
}

and then make a quirk in quirks.c that adds the software node property
for the Apple systems? Or something along those lines.

@Lukas, what do you think?