RE: [PATCH 5/6] PCI: acpiphp: look _RMV method a bit deeper in the hierarhcy

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

Mika Westerberg wrote:
> The acpiphp driver finds out whether the device is hotpluggable by checking
> whether it has _RMV method behind it (and if it returns 1). However, at
> least Acer Aspire S5 with Thunderbolt host router has this method placed
> behind device called EPUP (endpoint upstream port?) and not directly behind
> the root port as can be seen from the ASL code below:
> 
> Device (RP05)
> {
> 	...
> 	Device (HRUP)
> 	{
> 		Name (_ADR, Zero)
> 		Name (_PRW, Package (0x02)
> 		{
> 			0x09,
> 			0x04
> 		})
> 		Device (HRDN)
> 		{
> 			Name (_ADR, 0x00040000)
> 			Name (_PRW, Package (0x02)
> 			{
> 				0x09,
> 				0x04
> 			})
> 			Device (EPUP)
> 			{
> 				Name (_ADR, Zero)
> 				Method (_RMV, 0, NotSerialized)
> 				{
> 					Return (One)
> 				}
> 			}
> 		}
> 	}
> 
> If we want to support such machines we must look for the _RMV method a bit
> deeper in the hierarchy. Fix this by changing pcihp_is_ejectable() to check
> few more devices down from the root port.

We found that this approach is broken. We've got false positive: host
bridge itself was detected as hotplugable slot %) I think it's not
acceptable.

Mika has tried few more approaches, but we haven't found anything better
then hardcoded path like in original workaround patch[1]. It's not generic
at all, but safe from false positives.

Any thoughts?

[1] http://article.gmane.org/gmane.linux.kernel.pci/19102

-- 
 Kirill A. Shutemov