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SubjectRe: [PATCH 1/3] PCI Hotplug: workaround for Thunderbolt on Acer Aspire S5
[+cc Rafael]

On Thu, Dec 13, 2012 at 8:31 AM, Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> Correct ACPI PCI hotplug imeplementation should have _RMV method in a
> PCI slot (device under pci bridge). In Acer Aspire S5 case we have it
> deeper in hierarchy:
>
> Device (RP05)
> {
> // ...
> Device (HRUP)
> {
> // ...
> Device (HRDN)
> {
> // ...
> Device (EPUP)
> {
> // ...
> Method (_RMV, 0, NotSerialized) // _RMV: Removal Status
> {
> Return (One)
> }
> }
> }
> }
> }
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> drivers/pci/hotplug/acpi_pcihp.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
> index 2a47e82..d92ebfb 100644
> --- a/drivers/pci/hotplug/acpi_pcihp.c
> +++ b/drivers/pci/hotplug/acpi_pcihp.c
> @@ -422,6 +422,19 @@ static int pcihp_is_ejectable(acpi_handle handle)
> status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
> if (ACPI_SUCCESS(status) && removable)
> return 1;
> +
> + /*
> + * Workaround for Thunderbolt implementation on Acer Aspire S5.
> + *
> + * Correct ACPI PCI hotplug imeplementation has _RMV method in a PCI
> + * slot (device under pci bridge). In Acer Aspire S5 case we have it
> + * deeper in hierarchy.
> + */
> + status = acpi_evaluate_integer(handle, "HRDN.EPUP._RMV", NULL,
> + &removable);

I don't think encoding an ACPI path from the BIOS of a random machine
here is the right approach. The path components are completely
implementation-dependent, and we'll end up carrying this test forever,
long after the last Aspire S5 is in the landfill.

We need a more generic approach that covers this case. It would be
interesting to see the rest of the ACPI namespace details under
RP05.HRUP. I guess we have RP05.HRUP._ADR, at least. I'm not sure
what the BIOS is trying to tell us by providing
RP05.HRUP.HRDN.EPUP._RMV, but maybe we could figure it out if we knew
more about HRDN and EPUP.

> + if (ACPI_SUCCESS(status) && removable)
> + return 1;
> +
> return 0;
> }
>
> --
> 1.7.10.4
>
> --
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